Sealing and protection means for pumps, particularly for centrifugal pumps, equipped with sensors for monitoring the health status of the machine

Abstract

Sealing and protection means for a centrifugal pump, such pump comprising a rotor, or rotating part of the pump, formed by a shaft (2) on which impellers (3) are keyed enclosed in a casing (4) or fixed part of the pump. Such sealing means being interposed between the casing (4) and the impellers (3). Such sealing means comprising at least one fixed sealing ring (5) which is removably connected to the casing by means of locking means. Such sealing ring being able to maintain a predetermined gap (G) between the fixed parts and the moving parts of the pump, characterised in that such sealing means comprise sensor means for detecting some significant parameters of the life of the pump integrated in the sealing ring (5) itself.

Description

[0001] Sealing and protection means for pumps, particularly for centrifugal pumps, equipped with sensors for monitoring the health status of the machine

[0002] The present invention refers to sealing means for pumps that are interposed between the static parts and the rotating parts of such pumps. Such means are equipped with at least one sensor capable of measuring certain parameters that detect the state (health) of the pump itself.

[0003] Such sealing means generally comprise a ring or a wear bushing connected to the casing (fixed part of the pump) that surrounds the rotor (rotating parts) enclosed in such casing. The main function of such a ring is to prevent the leakage of fluid from high-pressure chambers to low-pressure chambers and also to allow the central positioning of the impellers and the entire rotor inside the casing without the need for additional locking elements.

[0004] The wear rings or bushings can be defined as a device used between the mobile rotating part of the pump and the fixed part.

[0005] In particular, in a centrifugal pump for transferring energy to the fluid, the impeller operates at high speeds. Unfortunately, these high speeds can cause excessive wear of the parts in contact between the impeller and the casing due to the deflection of the impeller shaft itself.

[0006] Such wear rings can be made of either a metallic material or a non-metallic material, for example, carbon or composite materials, such as glass-filled nylon, bronze-filled PTFE, glass-filled PTFE, phenolic, and PEEK.

[0007] Over time, the ring wears out and its function can be compromised. This wear problem is even more pronounced in radial seal multistage pumps.

[0008] Therefore, the need arose to monitor its wear and generally monitor the pump's condition through such a ring. Patent application US20200063872A1 describes a mechanical seal for a centrifugal pump having a rotating part comprising a first rotating sliding ring and a non-rotating part comprising a second sliding ring. The seal comprises a sensor positioned either on the rotating sliding ring or on the non-rotating sliding ring. The sensor is, for example, an acoustic, vibration, or acceleration sensor and is capable of monitoring the wear of the mechanical seal under normal operating conditions.

[0009] The present invention proposes sealing means equipped with sensors integrated into the wear rings or bushings.

[0010] One aspect of the present invention comprises sealing means for pumps, particularly for centrifugal pumps, provided with sensor means having the characteristics of claim 1.

[0011] Further features of the invention are included in the dependent claims.

[0012] The features and advantages of the sealing means according to the present invention will become more apparent from the following illustrative and non-limiting description, referring to the enclosed schematic drawings, in which:

[0013] • figures la, lb, and lc respectively illustrate, in perspective, top, and sectional views, a multistage pump to which the sealing means according to the present invention can be applied;

[0014] • figure 2 is a sectional view of a portion of the pump where the sealing means according to the present invention are located;

[0015] • figure 3 is a schematic view of the sealing means placed between the fixed part and the rotating part of the pump according to a first aspect of the invention,

[0016] • figure 4 is a vertical sectional view of the stator sealing ring of figure 3;

[0017] • figure 5 is a schematic view of the sealing means placed between the fixed part and the rotating part of the pump according to a second aspect of the invention; • figure 6 illustrates in a perspective view a possible embodiment of the stator sealing ring according to the second aspect of the present invention;

[0018] • figure 7 illustrates in a perspective view a possible embodiment of the rotating annular element according to the second aspect of the present invention;

[0019] • figure 8 illustrates in a perspective view of the sealing ring coupled to the rotating annular element of figures 6 and 7;

[0020] • figures 9a and 9b illustrate two examples of a coil associated with the sealing ring according to the second aspect of the present invention.

[0021] With reference to the cited figures, the sealing means according to the present invention are exemplarily applied to a centrifugal pump such as that illustrated in figures la, lb and lc, but can be applied to any type of pump that provides for the presence of such means, such as sealing rings arranged between the fixed and rotating parts of the pump itself.

[0022] Such illustrated centrifugal pump is a radial pump comprising a plurality of stages having a rotor (rotating part of the pump) formed by a shaft 2 on which impellers are keyed, such rotor being enclosed in a casing 4 (fixed parts of the pump).

[0023] Between the casing 4 and the impellers 3, such sealing and protection means are interposed, to prevent fluid leakage from high-pressure chambers to low-pressure chambers in all stages and to protect the surfaces of the main components of the pump. Such means comprise at least one fixed sealing ring 5 which is removably connected to the casing by means of locking devices, such as rivets, screws or other mechanical elements and / or adhesives, which surrounds these impellers 3. Such sealing means may also include at least one rotating annular element 6 associated with the rotating parts (i.e., the impellers) positioned in correspondence with this ring. Between the ring and the impellers or the rotating annular element associated with them, there is a thin gap G that must be kept as constant as possible, as explained in detail below. The interaction between the sealing ring 5 and the impeller 3 helps the centered positioning of the impellers and the entire rotor within the casing without the need for additional locking elements. The pressure profile that develops within the gap between the wear ring and the impeller is, in fact, capable of developing radial and tangential forces that tend to center the rotor around the axis of rotation.

[0024] The sealing rings 5 are generally made of wear-resistant materials with a low coefficient of friction to act as a wear element to be replaced when the material deterioration is such that the gap G exceeds an acceptable level, thus no longer ensuring correct pump operation.

[0025] According to a first aspect of the present invention, the sealing means comprise sensor means for detecting some significant parameters of the pump's life integrated into the sealing ring 5.

[0026] For the purposes of the present invention, examples of such significant parameters include the wear state of the sealing ring, the movement of the rotor (rotational speed), detection of the presence of liquid through the wear ring or bushing, and all sensors necessary for detecting the machine's status.

[0027] Such sensor means in one embodiment comprise a conductive filament 51 embedded in the ring. This filament can be advantageously arranged circumferentially so as to form a kind of coil within the ring itself.

[0028] Such filament is immersed in the ring at a predetermined depth P with respect to the inner surface 52 of the ring itself that faces the rotating parts 3 of the pump. Such filament, when powered by an electric current, functions as an ON / OFF sensor. Indeed, when the wear of the ring is below a certain depth (P), the conductive filament is correctly traversed by current, communicating a high voltage level to an external control unit, while with increasing wear, the filament emerges on the surface of the ring, and at the moment such wear reaches the defined depth limit (P), the filament will break, communicating a low voltage level to such external unit. The exact radius, therefore corresponding to the depth from the ring's surface, where the filament is placed determines the exact level of wear to be detected. According to an advantageous feature of the present invention, the wear ring with the filament inside is manufactured using 3D printing. Indeed, this technology allows for obtaining precise geometries without expensive tools, reducing production costs. It can contribute to customizing the design of wear rings for specific applications, optimizing clearance, material properties, and filament positioning. Preferably, such rings are made of high-performance composite materials, for example PEEK or printable materials with similar mechanical properties. The geometry of the filament as indicated above is preferably circular, and the cross-section can be of any type (circular, square, ...). In a further embodiment, such sensor means comprise a sensor for detecting rotor rotation. For example, a possible implementation technology for such a sensor involves the presence of at least one induction coil placed near the inner surface 52 of the ring and facing the rotors. The variation of the magnetic field induced by the rotation of the rotors and detected by the coil in ring 5, monitors the correct rotation.

[0029] In a further embodiment, such sensor means comprise in the sealing ring a sensor for detecting the presence of liquid in the gap G between the inner surface of the sealing ring and the rotor.

[0030] The detection from such sensor means can be brought outside the pump via known wireless technologies that do not require structural modifications to the pump casing. Alternatively, wired electrical connections can carry the sensor signals out of the pump, and through the same type of wired connection, the sensors can be electrically powered from outside the pump.

[0031] According to a second aspect of the present invention, such sealing means comprise an electrical energy generator including at least one permanent magnet 61 associated with the rotating annular element 6 and at least one coil 54 associated with the sealing ring 5.

[0032] When the annular element 6 rotates, due to the presence of the permanent magnet associated with it, it creates a variable magnetic field within the coil due to the relative motion between itself and the fixed wear ring.

[0033] According to Faraday's law of electromagnetic induction, this variable magnetic field induces an EMF (voltage) across the coil 54. This induced voltage can be utilized to power the sensor means described with reference to the first aspect of the invention and other electronic components inside the pump, without the need for any wired connection between the inside and outside of the pump itself.

[0034] Analogously to the first aspect of the invention, both the sealing ring with the coil inside it and the rotating annular element provided with a permanent magnet can be manufactured using 3D printing.

[0035] 3D printing can help customize the design of the wear ring for specific applications, optimizing clearance, material properties, and coil placement. Integrating the coil directly into the ring eliminates the need for separate components.

[0036] Figure 6 illustrates a feasibility demonstration of a sealing ring 5 comprising a plurality of seats 55 arranged (preferably equidistant from each other) along the circumference of the ring, within each of which a coil 54 is inserted.

[0037] Figure 7 illustrates an analogous embodiment of the rotating annular element 6 associated with the impellers 3, provided with a plurality of circumferentially arranged pockets 62 (preferably equidistant from each other) in each of which a permanent magnet 61 is inserted.

[0038] When the pump is assembled, the ring 5 and the annular element 6 appear as in Figure 8, such that the magnets and coils face each other, so that during rotation, the variable magnetic field generated by the magnets is optimally intercepted by the coils, generating an induced voltage sufficient to power sensors and electronic circuits inside the pump.

[0039] In the exemplary embodiment shown, eight seats and eight pockets are indicated, suitable for accommodating respective magnets and coils. In different embodiments, magnets, coils, pockets, and seats can have different shapes and numbers, always within the scope of the present invention.

[0040] Preferably, both the pockets and the seats are parallelepiped in shape, and the coils and magnets are shaped to fit into them. As illustrated in Figures 9a and 9b, the turns of the coils 61 can be quadrangular or circular.

Claims

CLAIMS1. Sealing and protection means for a centrifugal pump, such pump comprising a rotor, or rotating part of the pump, formed by a shaft (2) on which impellers (3) are keyed enclosed in a casing (4) or fixed part of the pump, such sealing means being interposed between the casing (4) and the impellers (3), such sealing means comprising at least one fixed sealing ring (5) which is removably connected to the casing by means of locking means, such sealing ring being able to maintain a predetermined gap (G) between the fixed parts and the moving parts of the pump, characterised in that such sealing means comprise sensor means for detecting some significant parameters of the life of the pump integrated in the sealing ring (5) itself.

2. Sealing means according to claim 1, wherein such sensor means comprise a conductive filament (51) immersed in the sealing ring (5).

3. Sealing means according to claim 1, wherein the filament is arranged circumferentially so as to form a sort of coil inside the ring itself.

4. Sealing means according to claim 2, wherein such filament is immersed in the ring at a predetermined depth (P) with respect to the internal surface (51) of the ring itself which faces the rotating parts (3) of the pump.

5. Sealing means according to claim 1, wherein such filament is powered by an electric current and when the wear of the ring is below a certain depth value (P), the conductive filament is crossed by current correctly communicating a high level of voltage to an external control unit, while as the wear increases the filament emerges on the surface of the ring and when such wear reaches the defined depth limit (P), the filament will break communicating a low level of voltage to such external unit.

6. Sealing means according to claim 2, wherein such wear ring with the filament inside it is made by 3D printing.

7. Sealing means according to claim 1, such sensor means further comprising a sensor for detecting the rotation of the rotors, a sensor for detecting the presence of liquid in the gap (G), and / or other sensors necessary for detecting the state of the machine.

8. Sealing means according to claim 1, further comprising at least one rotating annular element (6) associated with the rotating parts of the pump.

9. Sealing means according to claim 8, comprising an electrical energy generator including at least one permanent magnet (61) associated with the rotating annular element (6) and at least one coil (54) associated with the sealing ring (5) wherein when the annular element (6) rotates, by virtue of the presence of the permanent magnet associated therewith it creates a variable magnetic field inside the coil due to the relative motion between itself and the fixed wear ring (5) which induces an electric current in the coil (54).

10. Sealing means according to claim 9, wherein such electrical energy generator powers such sensor means.

11. Sealing means according to claim 9, wherein both the sealing ring with the coil inside it, and the rotating annular element provided with permanent magnet, are made by 3D printing.

12. Sealing means according to claim 9, wherein• said sealing ring comprises a plurality of seats (55) arranged alongthe circumference of the ring, inside which a coil (54) is inserted in each of them and wherein• said rotating annular element (6) is provided with a plurality of pockets (62) arranged circumferentially, in which a permanent magnet (61) is inserted in each pocket,• the ring (5) and the annular element (6) being assembled together so that the magnets and the coils are facing each other.

13. Sealing means according to claim 12, wherein both the magnets (61) and the coils (54) are arranged equidistant from each other.

14. Sealing means according to claim 12, wherein both the pockets (62) and the seats (55) are of parallelepiped shape and the coils and magnets are of a shape suitable for insertion therein.

15. Sealing means according to claim 14, wherein the turns of the coils (61) may be quadrangular or circular.

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