Sealing and protection means for pumps, in particular for self-powered centrifugal pumps

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 are keyed impellers (3) enclosed in a casing (4) or fixed part of the pump. Such sealing means being interposed between the casing (4) and the impellers (3) and such sealing means comprising at least one fixed sealing ring (5) which is removably connected to the casing by means of locking means and at least one rotating annular element (6) associated with the rotating parts of the pump. Such sealing ring being adapted to maintain a predetermined gap (G) between the fixed parts and the moving parts of the pump. Said sealing means comprise an electrical energy generator which includes 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), when the annular element (6) rotates, by virtue of the presence of the permanent magnet associated with it creates a variable magnetic field inside the coil due to the 15 relative motion between itself and the fixed wear ring (5) which induces an electric current in the coil (54).

Description

[0001] SEALING AND PROTECTION MEANS FOR PUMPS, IN PARTICULAR FOR SELF-

[0002] POWERED CENTRIFUGAL PUMPS

[0003] The present invention refers to sealing means for pumps that are interposed between the fixed parts and the rotating parts of such pumps.

[0004] 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 function of such ring is mainly to prevent the leakage of water from the high pressure chambers to the low pressure ones and also to allow the centered positioning of the impellers and the entire rotor inside the casing without the need for additional locking elements.

[0005] Wear rings or bushings can be defined as a device used between the rotating moving part of the pump and the fixed part.

[0006] In particular, in a centrifugal pump to transfer 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.

[0007] Such wear rings can be made of either a metallic or non-metallic material, for example, carbon or composite materials, such as glass-filled nylon, bronze-filled PTFE, glass-filled PTFE, phenolic and PEEK.

[0008] The ring wears out over time and its function can be compromised. This wear problem is even more pronounced on multistage radial seal pumps.

[0009] Therefore, the need arose to monitor its wear and to monitor the general condition of the pump through this ring.

[0010] The patent application US2020063872A1 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 able to monitor the wear of the mechanical seal under normal operating conditions.

[0011] The sensors associated with the sealing rings need to be electrically powered in order to correctly perform the measurements. This power supply can however be brought from outside the pump. This can be done through a wired connection, or, in the case where the sensor is a passive element (such as an RFID TAG) through a magnetic induction generated by a device external to the pump that activates the sensor and receives its signals after activation.

[0012] Both methods involve critical issues. In the case of a wired connection, it is necessary to structurally modify the pump casing to allow the passage of electrical conductors to and from any sensors (or in general electrical circuits) associated with the sealing ring, which is placed in a very delicate area (near the impellers) of the pump. In the second case, the electrical power that is sent to the sensor (or in general electrical circuits) is limited to a few milliwatts typical of RFID sensors, and therefore cannot power a significant quantity of sensors or circuits.

[0013] The present invention therefore proposes to solve the above-mentioned problems by equipping the sealing means with an autonomous generator of electrical energy that can be used inside the pump, without the need for external intervention.

[0014] An aspect of the present invention comprises sealing means for pumps, in particular for centrifugal pumps, having the characteristics of claim 1.

[0015] Further characteristics of the invention are included in the dependent claims.

[0016] The characteristics and advantages of the sealing means according to the present invention will be more evident from the following description, by way of example and not by way of limitation, referring to the attached schematic drawings in which:

[0017] • figures la, lb and lc illustrate respectively a perspective view, a top view and a section of a multistage pump to which the sealing means according to the present invention can be applied;

[0018] • figure 2 is a sectional view of a portion of the pump where the sealing means according to the present invention are located;

[0019] • Figure 3 is a schematic view of the sealing means placed between the fixed part and the rotating part of the pump comprising an electric generator according to the present invention,

[0020] • Figure 4 illustrates in perspective view a possible embodiment of the sealing ring according to the present invention;

[0021] • Figure 5 illustrates in perspective view a possible embodiment of the rotating annular element according to the present invention; • Figure 6 illustrates in perspective view the sealing ring coupled to the rotating annular element of Figures 4 and 5;

[0022] • Figures 7a and 7b illustrate two examples of coil associated with the sealing ring in accordance with the present invention.

[0023] With reference to the enclosed figures, the sealing means according to the present invention are applied by way of example to a centrifugal pump such as the one 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.

[0024] The 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, this rotor being enclosed in a case 4 (fixed parts of the pump).

[0025] These sealing and protection means are interposed between the case 4 and the impellers 3, to prevent the leakage of the fluid from the high pressure chambers to the 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 means, such as rivets, screws or other mechanical parts and / or adhesives, which surrounds such impellers 3. Such sealing means possibly also comprise at least one rotating annular element 6 associated with the rotating parts (i.e. the impellers) positioned in correspondence with such ring. Between the ring and the impellers or the rotating annular element associated with them there is a thin gap G which must be kept as constant as possible, as explained in detail below.

[0026] The interaction between the sealing ring 5 and the impeller helps the centered positioning of the impellers and the entire rotor inside the casing without the need for additional locking elements. The pressure profile that develops inside the gap between the wear ring and the impeller, in fact, is able to develop radial and tangential forces that tend to center the rotor around the rotation axis.

[0027] The sealing rings 5 are generally made of wearable materials with a low friction coefficient to act as a wear element to be replaced when the deterioration of the material is such as to make this gap G beyond an acceptable level, such as to no longer guarantee correct operation of the pump. According to 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.

[0028] When the annular element 6 rotates, by virtue of the presence of the permanent magnet associated with it, it creates a variable magnetic field inside the coil due to the relative motion between itself and the fixed wear ring 5.

[0029] According to Faraday's law of electromagnetic induction, this changing magnetic field induces an EMF (voltage) across coil 54. This induced voltage can be used to power sensors that measure the pump's state, the impellers of the seal rings themselves, and in general electrical circuits that may be present inside the pump body, without the need for any type of wired connection between the inside and outside of the pump itself.

[0030] Both the seal ring with the coil inside it, and the rotating annular element equipped with a permanent magnet, can be produced using 3D printing.

[0031] 3D printing allows for complex geometries without expensive tooling, reducing production costs. It can help customize wear ring designs for specific applications, optimizing clearance, material properties, and coil positioning. Integrating the coil directly into the ring eliminates the need for separate components.

[0032] Figure 6 illustrates a feasibility demonstration of a sealing ring 5 that comprises a plurality of seats 55 arranged (preferably equidistant from each other) along the circumference of the ring, inside which a coil 54 is inserted in each of them.

[0033] Figure 7 illustrates a similar embodiment of the rotating annular element 6 associated with the impellers 3, provided with a plurality of pockets 62 (preferably equidistant from each other) arranged circumferentially, in which a permanent magnet 61 is inserted in each pocket.

[0034] When the pump is assembled, the ring 5 and the annular element 6 appear as in figure 6 so that the magnets and the coils are facing each other, so that during rotation the variable magnetic field generated by the magnets is intercepted in an optimal way by the coils, generating an induced voltage sufficient to power sensors and electronic circuits inside the pump.

[0035] In the embodiment illustrated by way of example, eight seats and eight pockets are indicated, suitable for accommodating respective magnets and coils. In different embodiments, magnets, coils, pockets and seats can be of different shape and number, always within the scope of the present invention.

[0036] Preferably, both the pockets and the seats are of parallelepiped shape, and the coils and magnets are of a shape suitable for insertion therein. As illustrated in figures 7a and 7b, 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 are keyed impellers (3) 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 and at least one rotating annular element (6) associated with the rotating parts of the pump, such sealing ring being adapted to maintain a predetermined gap (G) between the fixed parts and the moving parts of the pump,, characterized in that such sealing means comprise an electrical energy generator which includes 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), when the annular element (6) rotates, by virtue of the presence of the permanent magnet associated with 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).

2. Sealing means according to claim 1, wherein such electric energy generator powers sensor means and in general electric circuits which may be present inside the pump body.

3. Sealing means according to claim 1, wherein both the sealing ring with the coil inside it, and the rotating annular element provided with a permanent magnet, are made by 3D printing.

4. Sealing means according to claim 1, wherein• said sealing ring comprises a plurality of seats (55) arranged along the 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.

5. Sealing means according to claim 4, wherein both the magnets (61) and the coils (54) are arranged equidistant from each other.

6. Sealing means according to claim 4, 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.

7. Sealing means according to claim 6, wherein the turns of the coils (61) may be quadrangular or circular.

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