Mechanical seal arrangement and sensor ring for monitoring operation of a mechanical seal arrangement

Abstract

The invention relates to a mechanical seal arrangement, the mechanical seal arrangement (10) having a rotating part (12), a non-rotating part (20) and a signal processing arrangement (30), the rotating part (12) comprising at least a rotating sliding ring (18) and a rotating sliding ring carrier (16), the non-rotating part (20) comprising at least a non-rotating sliding ring (24) and a non-rotating sliding ring carrier (22), and the signal processing arrangement (30) comprising at least one sensor (38, 48) for monitoring the operation of the mechanical seal arrangement, wherein a sensor ring (32) is arranged on the non-rotating sliding ring carrier (22), the sensor ring (32) being provided with the at least one sensor (38, 48) and means (34) for transmitting measurement data from the at least one sensor (38, 48) for further processing.

Description

TECHNICAL FIELD

[0001] The present invention relates to a mechanical seal arrangement according to the preamble of claim 1 and to a sensor ring according to the preamble of claim 11. BACKGROUND

[0002] Mechanical seals are increasingly accepted in various shaft sealing applications. Mechanical seals find use in various pumps, mixers and agitators. Mechanical seals have a relatively simple construction, are resistant to high temperatures and are relatively easy to maintain and repair. However, like various seals, it is difficult to predict their lifetime. It is also completely impossible to perform any visual monitoring of the condition of the seal. Therefore, the prior art comprises a number of documents discussing monitoring the condition of mechanical seals.

[0003] US-A-6,065,345 discusses a method of monitoring the condition of a mechanical seal in a device provided with a rotating part, in particular in a pump having a rotating shaft for conveying a fluid. The acoustic emission of the seal is continuously measured at discrete times in the operating state of the device and at least one statistical characteristic value is obtained from the acoustic signal. The object of the above discussed patent is to monitor the sliding condition of the seal. In other words, if the seal starts to run dry, i.e. the flush is not working properly for some reason, the acoustic emission from the seal changes with the condition of the lubrication film. The US patent also discusses the influence of the rotational speed of the pump, the temperature of the flush liquid, the pressure of the fluid to be pumped, etc. on the acoustic emission of the seal, whereby the acoustic emission can change even if the sliding condition is not changed.

[0004] US-B1-6,360,610 discusses a system and method particularly adapted to monitor the interface of two liquid-lubricated mechanical seal faces. The system monitors the interface by generating ultrasonic shear waves using a wave source, directing the waves toward the interface, detecting the waves after they have interacted with the interface, and comparing the detected waves to predetermined wave characteristics. Based on the comparison, an alarm can be triggered. The alarm can indicate that the mechanical seal is failing. In a preferred example, the method involves detecting collapse of the lubrication film between the seal faces and detecting excessive rough contact. Collapse of the lubrication film and excessive rough contact are precursors to seal failure. An ultrasonic transducer is placed behind one of the seal faces and used to generate ultrasonic shear waves (at a known frequency and amplitude) that propagate toward the interface between the two seal faces. By monitoring the amplitude of the waves transmitted through the interface or reflected by the interface, film collapse and the degree of contact between the faces can be detected.

[0005] Still another document discussing the condition of the fluid film between the sliding surfaces is GB-A-2430034. It discloses a condition monitoring system using at least one acoustic emission sensing device to indirectly and / or remotely monitor the health status of a piece of rotating equipment and its application as, for example, a mechanical seal or bearing assembly. The acoustic emission sensing device can be placed in direct or indirect contact with the counter-rotating surface. The signals emitted by the acoustic emission sensing device can be amplified, filtered from background noise, calculated, compared with reference values and stored on a data storage device.

[0006] US-B2-8,527,214 discusses a mechanical device showing the degree of wear of the sliding surfaces of a mechanical seal. On the one hand, the mechanical device discussed is a simple device measuring the physical axial movement of the sliding ring due to wear, but on the other hand, in most applications it is practically quite difficult to arrange this device in mechanical contact with the mechanical seal. In particular, as indicated in the patent, it would also be difficult to arrange the follower in mechanical contact with the rotating sliding ring carrier whose axial movement is to be measured.

[0007] In other words, the prior art cited above discusses abnormal operating conditions in which the lubrication of the surfaces of the mechanical seal has failed or will fail, resulting in dry running of the seal, or wear under normal operating conditions. However, according to the prior art, the monitoring of dry running or wear under normal operating conditions requires such an arrangement that, although simple in principle, is difficult to construct and includes a high risk of functional failure, since the follower discussed in the patent cited (US-B2-8,527,214) is also subject to wear.

[0008] In addition to the prior art documents discussed above, it is also necessary to mention EP-B1-2362122. The European patent document lists a plurality of sensors to be arranged in or on a mechanical seal, preferably in or close to the sealing gap between the rotating and non-rotating sealing surfaces. The European patent document lists the following operating parameters that can be tracked: the pressure of the working fluid close to the seal, the temperature of the working fluid, the temperature at the sealing gap, the leakage flow through the sealing gap, the rotational speed of the shaft and / or the vibrations of the sealing arrangement. However, the document does not discuss the way in which the various sensors are arranged in connection with or in communication with the mechanical seal.

[0009] Document WO2018210504 A1 discloses a mechanical seal provided with a sensor arranged to the sliding ring carrier of the non-rotating part of the seal.

[0010] Document GB2395532 A discloses a mechanical seal device comprising one or more sensors monitoring any force, torque or vibration transmitted from the sealing area to the spring plate via the stationary sealing face 31.

[0011] Document CN 10710099 B discloses an oil-immersed centrifugal sealing device. There is an axial sealing ring arranged against a rotating shaft, the sealing ring having an inner circumferential groove, a distance detection sensor being arranged in the inner circumferential groove for measuring the gap between the axial sealing ring and the outer peripheral surface of the rotating shaft.

[0012] In almost all prior art cases, the condition of the seal is monitored more or less by external sensors, which is quite understandable, since it is not easy to access the mechanical seal, and there are no simple devices on the market for monitoring the condition of the seal.

[0013] The object of the present invention is to provide an inventive mechanical seal arrangement and sensor that significantly improves the performance of the mechanical seal compared to prior art solutions. SUMMARY

[0014] At least one of the objects of the present invention is essentially met, as disclosed in the independent claim and the more detailed other claims describing different embodiments of the invention.

[0015] According to an embodiment of the present invention, the mechanical seal arrangement has a rotating part comprising at least a rotating sliding ring and a rotating sliding ring carrier, a non-rotating part comprising at least a non-rotating sliding ring and a non-rotating sliding ring carrier, and a signal processing arrangement comprising at least one sensor for monitoring the operation of the mechanical seal arrangement. The mechanical seal arrangement comprises a sensor ring provided on the non-rotating sliding ring carrier, the sensor ring being provided with at least one sensor and means for transmitting measurement data from the at least one sensor for further processing, the sensor ring having a first wall and a second wall, a cavity being left therebetween, wherein the cavity is open in a radially inward direction, wherein at least one opening is arranged in the second wall, the at least one sensor being arranged to extend from the cavity to the outside of the sensor ring through the at least one opening.

[0016] According to an embodiment of the present invention, the mechanical seal comprises at least one opening in the non-rotating sliding ring carrier for the at least one sensor.

[0017] According to an embodiment of the present invention, the opening in the second wall of the sensor ring and the opening in the non-rotating sliding ring carrier are coaxial with each other and together extend from the cavity to the non-rotating sliding ring, so that the at least one sensor is in contact with the non-rotating sliding ring. In this way, a direct measurement from the sliding ring is obtained.

[0018] According to embodiments of the present application, the at least one sensor is a temperature or vibration sensor.

[0019] According to embodiments of the present application, the sensor ring comprises at least one opening at its first wall for at least one sensor.

[0020] According to embodiments of the present application, the at least one sensor is a pressure sensor.

[0021] According to embodiments of the present application, the cavity in the sensor ring is an annular cavity in the inner circumference of the sensor ring.

[0022] According to embodiments of the present application, the cavity in the sensor ring is at least one groove arranged in the inner circumference of the sensor ring. The groove extends in at least one direction only partially around the inner circumference of the sensor ring from or past at least one opening arranged in the second wall of the sensor ring.

[0023] According to embodiments of the present application, the sensor ring is sealed to the non-rotating slide ring carrier by means of at least one O-ring and at least one annular flat seal.

[0024] According to embodiments of the present application, the sensor ring is fastened to the non-rotating slide ring carrier by means of screws.

[0025] According to embodiments of the present application, a signal processing unit (SPU) receives measurement data from the at least one sensor via the transmission means.

[0026] A sensor ring according to the present application is intended for monitoring the operation of a mechanical seal arrangement. The sensor ring comprises a first wall and a second wall and a cavity therebetween, the cavity being open in a radially inward direction, at least one of the first wall and the second wall comprising at least one opening for at least one sensor.

[0027] According to embodiments of the present application, the sensor ring has a first wall and a second wall, a cavity being left therebetween, wherein the cavity is open in a radially inward direction, and wherein at least one opening is arranged in the second wall, the at least one sensor being arrangeable to extend from the cavity to the outside of the sensor ring through the at least one opening when mounted for use.

[0028] According to embodiments of the present application, the cavity in the sensor ring is an annular cavity in the inner circumference of the sensor ring.

[0029] According to embodiments of the present application, the cavity in the sensor ring is at least one groove arranged in the inner circumference of the sensor ring.

[0030] According to an embodiment of the present application, it is characterized by means for transmitting data measured by the at least one sensor for further processing.

[0031] According to an embodiment of the present application, the transmission means is one of a wire, a fiber optic cable, an RF connection and a Bluetooth connection.

[0032] By means of the present application, the reliability and / or predictability of the mechanical seal arrangement is significantly improved.

[0033] Additionally or alternatively, the mechanical seal according to the present application can be provided with a reliable and simple means for monitoring the operation of the mechanical seal under normal operating conditions.

[0034] Further, the present application introduces a simple "sensor ring" that can be arranged to be connected with all types of mechanical seals, including single- and double-acting mechanical seals.

[0035] The exemplary embodiments of the present application presented in this patent application should not be interpreted as a limitation on the applicability of the appended claims. The verb "comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in the dependent claims are mutually freely combinable unless otherwise explicitly stated. The novel features considered as characteristic of the present application are particularly set forth in the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0036] In the following, the mechanical seal arrangement and the sensor ring of the present application are described in more detail with reference to the accompanying exemplary drawings, in which

[0037] Figure 1 shows a partial axial cross-section of a mechanical seal arrangement according to a preferred embodiment of the present application,

[0038] Figure 2 shows a cross-section of a sensor ring with its sealing means,

[0039] Figure 3 shows an isometric view of a non-rotating slide ring carrier with Figure 1 a sensor ring of a mechanical seal arrangement, and

[0040] Figure 4 shows an isometric view of a sensor ring of the present application. DETAILED DESCRIPTION

[0041] Figure 1A mechanical seal arrangement according to a preferred embodiment of the present application is illustrated, said seal arrangement comprising a single acting mechanical seal 10 and a signal processing arrangement 30, which are illustrated schematically and exemplarily. The present application is of course also applicable to a double acting mechanical seal. The mechanical seal 10 is used to seal a shaft 8 (illustrated with a dashed line) of e.g. a flow machine, such that the interior of the flow machine (at the left hand side of the seal 10) is kept separated from the atmosphere (at the right hand side of the seal 10). The mechanical seal 10 is positioned in a seal chamber provided within a specific seal housing or a housing cover of the flow machine.

[0042] The mechanical seal 10 comprises a rotating part 12 and a non-rotating part 20. The rotating part 12 comprises a retainer ring 14, a rotating slide ring carrier 16 and a rotating slide ring 18. The rotating slide ring 18 is attached to an axial end of the rotating slide ring carrier 16. The non-rotating part 20 comprises a non-rotating slide ring carrier 22, a non-rotating slide ring 24 and a gland ring 26. The non-rotating slide ring 24 is attached to an end of the non-rotating slide ring carrier 22. When used in a flow machine, the slide rings 18 and 24 are in mechanical contact with each other. In addition to the illustrated components, the mechanical seal can comprise O-rings, drive pins, set screws and bolts, which have not been discussed in more detail as they do not form part of the present application.

[0043] The signal processing arrangement 30 comprises a signal processing unit SPU, a sensor ring 32 with sensors 38 provided in connection therewith and means 34 for transmitting data measured by the sensors 38 to the signal processing unit SPU. The sensor ring 32 is a separate ring element arranged on the non-rotating part 20 of the mechanical seal. The sensor ring does not have an essential direct function in the operation of the mechanical seal itself and its function relates to keeping the sensors adapted to obtain accurate measurement results and keeping the transmission means 34. The transmission means 34 can be conventional wires, optical fiber cables or wireless transmission means, such as Bluetooth or radio frequency transmission means, to name a few alternative means, without the intention to limit the present application to the listed alternatives.

[0044] The rotating part 12 of the mechanical seal 10 is assembled on the shaft such that the retainer ring 14 is mounted against a shoulder on the shaft 8, typically between the shoulder and a hub of e.g. a centrifugal impeller, and the rotating slide ring carrier 16 with the rotating slide ring 18 fastened to its end is pushed onto the O-ring provided on the retainer ring 14.

[0045] The non-rotating part 20 of the mechanical seal is assembled such that the sensor ring 32 is first pushed onto the non-rotating slide ring carrier 22 against the radially outwardly extending flange-like portion 28 of the non-rotating slide ring carrier 22. The sensor ring 32 can be fastened to the flange-like portion 28 in the axial direction or to the cylindrical portion of the slide ring carrier 22 in the radial direction. AsFigure 2 The sensor ring 32 shown in Figs. 1 1 to 13 is provided with a radial seal 40 and an axial seal 44 and is assembled in a sealing manner on the non-rotating sliding ring carrier 22. The sensor ring 32 is sealed to the cylindrical portion of the sliding ring carrier 22 in the radial direction by means of at least one O-ring 40 provided at the inner circumference of the first wall 42 of the sensor ring 32 and, preferably but not necessarily, to the flange-like portion 28 in the axial direction by means of an annular flat seal 44 provided on the outer surface of the second wall 46 of the sensor ring 32. Thereafter, the non-rotating sliding ring carrier 22 is coupled to the gland ring 26, preferably in a non-rotating but preferably but not necessarily axially movable manner (possibly holding the sliding ring carrier 22 non-rotating with the help of a drive pin and allowing axial movement of the non-rotating sliding ring with the help of a spring) and the gland ring 26 is pushed inside the opening in the housing of the flow machine and fastened thereto. Thus, the rotating sliding ring 18 and the non-rotating sliding ring 24 fastened at the end of the non-rotating sliding ring carrier 22 are brought into mechanical contact with each other.

[0046] In this embodiment of the application, in addition to in Figure 1 , the sensor ring 32 shown in Figure 2 , Figure 3 and Figure 4 is provided with a substantially axial bore 36 for fastening the sensor ring 32 to the flange-like portion 28 of the non-rotating ring carrier 22, sensors 38, 48 required for observing at least one operating parameter of the mechanical seal and monitoring the operation of the mechanical seal, and transmission means 34 for transmitting the data measured by the sensors 38, 48, i.e. the so-called measurement data, to the signal processing unit SPU. The sensors 38 can be temperature, acoustic or vibration sensors, to name just a few alternative solutions, however, the application is not limited to the specified alternatives. The sensor ring comprises an opening 50' arranged through the second wall 46 of the sensor ring 32. There is also an opening 50'' arranged through the flange-like portion 28 of the non-rotating ring carrier 22, so that the sensor 38 can be passed through the opening 50' in the sensor ring 32 and the flange-like portion 28 in the non-rotating ring carrier 22 to be in direct contact with the non-rotating sliding ring 24. The openings are advantageously axial with respect to the ring carrier 22 and arranged coaxially with each other.

[0047] Figure 3 and Figure 4 The sensor 48 in Figs. 1 1 to 13 is a pressure sensor configured to record the fluid pressure in front of the mechanical seal 10. Thus, the sensor 48 is provided in an opening 52 in the first wall 42 of the sensor ring 32. In addition to the pressure in the sealing space, the temperature therein can also be tracked by means of the application, to name just two alternative solutions, however, the application is not limited to the specified alternatives only.

[0048] Preferably, the sensor ring 32 has a U-shaped cross-section, leaving an internal cavity 54 within the sensor ring 32 between its first wall 42 and its second wall 46, which, when in use, opens radially inwardly to the non-rotating sliding ring carrier 22, so that the sensors 38 and 48, and especially the transmission means (i.e. e.g. its wires) can be arranged in the internal cavity 54 without contact with the liquid surrounding the mechanical seal. The cavity 54 in the sensor ring 32 can be an annular cavity extending over the entire inner circumference of the sensor ring 32, or it can be formed by at least one groove machined or otherwise provided in the inner circumference of the sensor ring 32 to extend from the sensors 38, 48 to an opening 56 provided for taking the transmission means 34 from the sensors out of the sensor ring 32. The opening 56 is advantageously arranged to extend radially through the bottom of the cavity 54. The transmission means 34, when it is a mechanical wire, an optical cable or a set of wires or cables, is preferably guided along a single channel to the signal processing unit SPU. The channel can be guided through the gland ring 26 or through the bearing housing or housing cover (i.e. through any machine element surrounding the mechanical seal) to the signal processing unit SPU.

[0049] While the application has been described herein by way of example with reference to embodiments thereof that are presently considered to be the most preferred, it is to be understood that the application is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of features disclosed, and numerous other applications included within the scope of the application as defined by the appended claims. The details in the above description are intended to give specific examples of the application. The details can be varied, and the application is not limited to the details given.

Claims

1. A mechanical seal arrangement, the mechanical seal arrangement (10) having a rotating part (12), a non-rotating part (20) and a signal processing arrangement (30), the rotating part (12) comprising at least a rotating sliding ring (18) and a rotating sliding ring carrier (16), the non-rotating part (20) comprising at least a non-rotating sliding ring (24) and a non-rotating sliding ring carrier (22), and the signal processing arrangement (30) comprising at least one sensor (38, 48) for monitoring the operation of the mechanical seal arrangement, a sensor ring (32) provided on the non-rotating sliding ring carrier (22) and provided with the at least one sensor (38, 48), and a transmission device (34) for transmitting measurement data from the at least one sensor (38, 48) for further processing, characterized in that, The sensor ring (32) is a separate ring element having a first wall (42) and a second wall (46) leaving a cavity (54) between the first wall and the second wall, the cavity (54) comprising at least one groove arranged in an inner circumference of the sensor ring (32), wherein the cavity (54) opens in a radially inward direction and at least one of the first wall (42) and the second wall (46) comprises at least one axial opening (50', 52) for at least one sensor (38, 48).

2. Mechanical seal arrangement according to claim 1, characterized in that At least one opening (50') is arranged in the second wall (46), the at least one sensor (38) being arranged to extend through the at least one opening (50') from the cavity (54) to the outside of the sensor ring (32).

3. The mechanical seal arrangement of claim 1, wherein: At least one opening (50'') is arranged in the non-rotating slide ring carrier (22) for the at least one sensor (38).

4. The mechanical seal arrangement of claim 2, characterized in that: The at least one opening (50') in the second wall (46) of the sensor ring (32) and the at least one opening (50'') in the non-rotating slide ring carrier (22) are coaxial to each other and together extend from the cavity (54) to the non-rotating slide ring (24) to bring the at least one sensor (38) into contact with the non-rotating slide ring (24).

5. The mechanical seal arrangement according to any one of claims 1 - 3, characterized in that: The sensor ring (32) has at least one opening (52) at its first wall (42) for at least one sensor (48).

6. The mechanical seal arrangement of claim 4, characterized in that: The at least one sensor (48) is a pressure sensor.

7. The mechanical seal arrangement of claim 1, wherein: The cavity (54) in the sensor ring (32) is an annular cavity in an inner circumference of the sensor ring (32).

8. The mechanical seal arrangement of claim 1, wherein: The cavity (54) in the sensor ring (32) comprises at least one groove arranged in the inner circumference of the sensor ring (32).

9. The mechanical seal arrangement of claim 1, wherein: The sensor ring (32) is sealed to the non-rotating slide ring carrier (22) by means of at least one O-ring (40) and at least one annular flat seal (44).

10. The mechanical seal arrangement of claim 1, wherein: A signal processing unit (SPU) is provided for receiving the measurement data from the at least one sensor (38, 48) via the transmission device (34).

11. A sensor ring for monitoring operation of a mechanical seal arrangement, the sensor ring (32) comprising a first wall (42) and a second wall (46) and having a U-shaped cross section, leaving a cavity (54) between the first wall (42) and the second wall (46), the cavity (54) being an annular cavity in an inner circumference of the sensor ring (32) and comprising at least one groove arranged in the inner circumference of the sensor ring (32) opening in a radially inward direction, characterized in that: At least one of the first wall (42) and the second wall (46) comprises at least one axial opening (50', 52), at least one sensor (38, 48) is arranged in the at least one axial opening (50', 52), and the at least one groove extends at least partially around the inner circumference of the sensor ring.

12. The sensor ring of claim 11, wherein: The at least one groove in the inner circumference of the sensor ring (32) extends from the at least one opening (50', 52) for at least one sensor (38, 48) to an opening (56) arranged to extend radially through a bottom of the cavity (54).

13. The sensor ring of claim 12, wherein: The sensor ring (32) has a first wall (42) and a second wall (46) with a cavity (54) left therebetween, wherein the cavity (54) opens in a radially inward direction, and wherein at least one opening (50') is arranged in the second wall (46), through which at least one sensor (38) can be arranged to extend from the cavity (54) to the outside of the sensor ring (32) when mounted for use.

14. The sensor ring of claim 13, wherein: transmission means (34) for transmitting data measured by the at least one sensor (38, 48) for further processing, the transmission means (34) being one of a wire, a fiber optic cable, an RF connection and a Bluetooth connection.

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