EP3529494A1

EP3529494A1 - Canned motor pump and method for manufacturing such a motor pump

Info

Publication number: EP3529494A1
Application number: EP17787509.3A
Authority: EP
Inventors: Emile Thomas Di Serio; Xavier DE BENGY
Original assignee: Saint Jean Industries SAS
Current assignee: Saint Jean Industries SAS
Priority date: 2016-10-19
Filing date: 2017-10-05
Publication date: 2019-08-28
Also published as: US20200056616A1; FR3057626A1; MA46556A; CN110036205A; WO2018073508A1

Abstract

The invention relates to a canned motor pump (P1) comprising: a housing (10) including a body (11) and a motor casing (12); an electric motor (20) including a stator (30) and a rotor (40) arranged in the motor casing (12); a shaft (50), extending along a central axis (X1), secured with the rotor (40) to rotate therewith about the central axis (X1), and having a front end (52) located outside the motor casing (12), in the body (11) of the housing (10); and a wheel (60) located at the front end (52) of the shaft (50), secured with the shaft (50) to rotate therewith about the central axis (X1) and having a hydraulic profile suitable for moving a fluid (F) in the body (11). The rotor (40), the shaft (50) and the wheel (60) form a rotary assembly (ER1). Within the rotary assembly (ER1), only the shaft (50) is supported by one or more bearings (80), thereby rotatably guiding the rotary assembly (ER1). The motor pump (P1) is characterised in that the shaft (50) and the wheel (60) form, at least partially, a single-piece part (70). A method for manufacturing such a motor pump (P1) is also described.

Description

Motor-driven motor pump, and method for manufacturing such a motor-pump

The present invention relates to a motor pump with a drowned rotor. The invention also relates to a method of manufacturing such a motor pump.

By definition, a flooded motor pump comprises both a pump and a motor, arranged in a hermetically sealed housing. The motor pump includes an inlet opening and a fluid outlet opening. When the motor pump is integrated into an industrial installation, sealing is also ensured at the inlet and outlet openings.

Various constructions of motor-driven motor pumps are known for example from EP2607709A1, JP2007127135A, US6010319A and WO200123763A1.

These motor pumps include a housing, an electric motor, a central shaft and a wheel. The housing includes an engine casing. The electric motor comprises a stator and a rotor arranged in the motor casing. The shaft, the rotor and the wheel form a rotating assembly. The central shaft is supported by two bearings. The wheel is attached to the front end of the shaft, located outside the motor casing.

In US6010319A, the shaft and the wheel are distinct. The sleeve formed in the central part of the wheel is simply a part of this wheel, intended for mounting on the shaft. This sleeve does not provide rotational guidance of the rotary assembly. In this case, the sleeve of the wheel constitutes a means of fixing the wheel to the shaft by shrinking, but can not be considered as constituting a part of the shaft, being unable to provide the guiding function rotation proper to the tree. In addition, it is possible to change the wheel independently of the shaft.

The object of the present invention is to provide an improved motor pump.

For this purpose, the subject of the invention is a motor-driven pump, comprising: a casing including a body and a motor casing; an electric motor including a stator and a rotor disposed in the motor casing; a shaft which extends along a central axis, which is integral with the rotor in rotation about the central axis, and which has a front end located outside the motor casing, in the body of the casing; and a wheel which is located at the front end of the shaft, which is integral with the shaft in rotation about the central axis, and which has a hydraulic profile adapted to the displacement of a fluid in the body. The rotor, the shaft and the wheel form a rotating assembly. Within the whole rotary, only the shaft is supported by one or more bearings, thus ensuring the rotational guidance of the rotating assembly. The motor pump is characterized in that the shaft and the wheel are at least partly a single piece. Thus, the motor pump according to the invention offers many advantages. Thanks to the flooded rotor, the motor pump has an absolute seal, high reliability and low maintenance. The one-piece piece formed by the shaft and the wheel can be manufactured according to different techniques, in particular by additive manufacturing of the part or mold in which this part is cast. This offers responsiveness and freedom for the design of geometric shapes to improve the efficiency of the motor pump. In particular, a great freedom of design is offered at the level of the central part of the wheel. This also improves the NPSH characterizing the suction performance of the motor pump. Coupled with the synchronous motor, shorter and retaining its very high energy efficiency even with a large air gap, the design is simplified by being more compact and with fewer components. The large air gap makes it possible to envisage new sealing solutions for the stator, improving the efficiency of the motor and therefore of the motor pump.

In addition, the motor pump according to the invention has a great versatility. This motor pump can be implemented in the context of many industrial or domestic applications: agribusiness, chemistry, pharmaceuticals, hydrocarbons, phosphoric fertilizers, metallurgy, marine, boiler, desalination, evaporation, etc.

According to other advantageous characteristics of the motor pump according to the invention, taken separately or in combination:

- The shaft and the wheel are integrally a single piece.

- The wheel has a central portion, which is located on the central axis, belongs to the single piece, and is devoid of fixing system.

- The central part forms a booster propeller.

- The central part includes an extension of the blades of the wheel.

- The motor pump comprises a single bearing which supports the shaft radially to the central axis for rotating the rotary assembly, and which is located between the rotor and the wheel along the central axis.

- The motor pump comprises a front bearing and a rear bearing which support the shaft radially to the central axis for rotating the rotary assembly, the front bearing being located between the rotor and the wheel along the central axis. - The electric motor is built using synchronous motor technology with rotor magnets.

- The stator, comprising an electromagnetic core and a coil, has an inner surface completely enveloped in a non-metallic material, facing the rotor and in contact with the fluid flowing in the motor casing.

- The stator is embedded in a sealed resin coating, at least along the inner surface.

- The motor pump is a centrifugal pump, the hydraulic profile of the wheel being adapted to the energy transmission by centrifugation of the fluid.

The invention also relates to a method of manufacturing a motor pump as mentioned above. According to this method, the shaft and the wheel are at least partly made in the form of a one-piece piece, for example according to a technique of sand molding, metal mold or lost wax, sintering, welding, additive manufacturing, or a combination of several techniques.

According to a first particular mode, the method comprises an additive manufacturing operation of the one-piece part.

According to a second particular embodiment, the method comprises an additive manufacturing operation of at least one part of a mold including a print corresponding to the one-piece part, and then an operation of manufacturing the one-piece part in this mold. The additive manufacturing operation may consist of manufacturing the mold in its entirety, or only a part of this mold, especially at the junction between the shaft and the wheel.

Preferably, the shaft and the wheel are integrally manufactured as a single piece.

The method may also include other operations without departing from the scope of the invention. For example, the method may include machining, heat treating, coating, etc. operations. The invention will be better understood on reading the following description, given solely by way of non-limiting example and with reference to the appended diagrammatic drawings in which:

Figure 1 is a longitudinal section of a motor pump according to the state of the art;

FIG. 2 is an enlarged view of detail II in FIG. 1; Figure 3 is a longitudinal section similar to Figure 1, showing a motor pump according to a first embodiment of the invention;

Figure 4 is an enlarged view of detail IV in Figure 3;

Figure 5 is a longitudinal section similar to Figure 1, showing a motor pump according to a second embodiment of the invention; and Figure 6 is a longitudinal section similar to Figure 1, showing a shaft variant designed to equip a motor pump according to the invention.

FIGS. 1 and 2 show an example of a centrifugal pump PO with a drowned rotor known from the state of the art.

The pump unit PO comprises a housing 1, an electric motor 2, a shaft 5, a wheel 6, a screw 7 and bearings 8 and 9. The electric motor 2 includes a stator 3 and a rotor 4 centered on a central axis X1. The rotor 4 is secured to the shaft 5, itself secured to the wheel 6. The screw 7 serves to fix the wheel 6 at the end of the shaft 5. The rotor 4, the shaft 5 and the wheel 6 form a rotating assembly, movable in rotation around the central axis X1.

The casing 1 is partially shown for the sake of simplification. The casing 1 includes a body 1 partially represented by dashed lines, a motor casing 1b and a lid 1c. The stator 3 and the rotor 4 are arranged in the motor casing 1b. The lid 1c closes the motor casing 1b at the rear bearing 9.

The stator 3 comprises an electromagnetic core 3a, a winding 3b, a resin coating 3c and a metal jacket 3d. The winding 3b extends on either side of the core 3a along the axis X1 and is embedded in the coating 3c. The 3d jacket extends all along the stator 3, at the air gap formed with the rotor 4, to seal the stator 3. The 3d jacket is in contact with both the core 3a and the coating 3c. This configuration is a source of eddy current losses in the 3d jacket.

FIGS. 3 and 4 show a centrifugal motor pump P1 with a drowned rotor according to a first embodiment of the invention.

The pump P1 comprises a housing 10, an electric motor 20 including a stator 30 and a rotor 40, a shaft 50, a wheel 60 and a bearing 80. The electric motor 20 includes a stator 30 and a rotor 40 centered on a central axis X1. The rotor 40 is integral with the shaft 50, itself secured to the wheel 60, as detailed below.

The housing 10 includes a body 1 1 disposed on the front side and a motor casing 12 disposed on the rear side of the motor pump P1. The body 11 is partially represented by dashed lines for purposes of simplification. The envelope 12 comprises different walls 14, 15, 16 and 18 integral with each other. The outer wall 14 has a cylindrical profile. The front wall 15 has a flat annular shape, surrounding the wall 18. The rear wall 16 has a flat disk shape. The front wall 18 has a cylindrical shape and constitutes a bearing support.

The stator 30 comprises an electromagnetic core 31 and a coil 32, which extends on either side of the core 31 along the axis X1. The core 31 and the coil 32 are embedded in a resin coating 33, thus sealing the stator 3. The coating 33 extends all along the stator 30, at the gap formed with the rotor 40 The stator 30 is devoid of a metal jacket. By using the coating 33 to replace the metal jacket of the stator 30, the eddy current losses are suppressed. According to the invention, the shaft 50 and the wheel 60 constitute at least partly a one-piece part 70. In other words, the part 70 comprises at least a portion of the shaft 50 and at least a portion of the wheel 60. or several other parts of the shaft 50 and / or the wheel 60 may be formed by one or more different parts of the part 70.

According to a preferred embodiment, shown in the figures, the shaft 50 and the wheel 60 constitute integrally a single one-piece piece 70. In other words, the piece 70 materializes the entirety of the shaft 50 and the wheel 60. Those there are no other rooms than room 70.

By way of nonlimiting examples, the part 70 may be manufactured according to various techniques of sand molding, metal mold or lost wax, sintering, welding, additive manufacturing of the part 70, additive manufacturing of the mold, or a combination of several techniques.

Advantageously, the part 70 can be manufactured entirely by additive manufacturing. According to an equally advantageous alternative, this part 70 can be cast in a mold, itself obtained at least in part by additive manufacturing.

The rotor 40 and the part 70 form a rotary assembly ER1, rotatable about the axis X1, within the pump P1. The shaft 50 extends along the axis X1, with a running portion 51 connecting a front end 52 and a rear end 53. The rotor 40 is secured to the shaft 50 in its current portion 51, by any known means. The current portion 51 and the rear end 53 are located in the motor casing 12. The front end 52 is located outside the motor casing 12, in the body 1 1 of the casing 10.

The wheel 60 comprises a central portion 61, blades 62, an inlet opening 63, internal channels 64 and outlet orifices 65. The wheel 60 is located outside the motor casing 12, in the body 1 1 of the casing 10. The wheel 60 has a hydraulic profile adapted to the displacement of a fluid F in the body 1 1. More specifically, the pump P1 is a centrifugal pump, that is to say that the hydraulic profile of the wheel 60 is adapted to the energy transmission by centrifugation of the fluid F in the pump P1. The fluid F enters the opening 63, then passes through the channels 64 formed in the wheel 60, to the outlet orifices 65.

The central portion 61 is located on the axis X1 and integral with the front end 52 of the shaft 50. As the shaft 50 and the wheel 60 constitute the part 70, the central portion 61 may be devoid of a fixing system , for example screw type 7, provided in the state of the art. This provides greater design freedom at this central portion 61.

In the example of FIG. 3, the central portion 61 has a concave shape, projecting from the front side, so as to guide the fluid F entering the opening 63 and then the channels 64.

Alternatively, the central portion 61 may be shaped into a booster propeller. According to another alternative, the central portion 61 may include an extension of the blades 62 of the wheel 60. These two alternatives may be combined.

Within the rotary assembly ER1, only the shaft 50 is supported by the bearing 80. In other words, only the shaft 50 ensures the rotational guidance of the rotary assembly ER1, together with the bearing 80.

The bearing 80 is located between the rotor 40 and the wheel 60 along the axis X1. The bearing 80 can therefore be called a central bearing, relative to the rotary assembly ER1. The bearing 80 is constituted by the wall 18 and two elements 81 and 82, which are housed in the bore delimited by the wall 18. The elements 81 and 82 are slightly spaced, and support the running portion 51 of the shaft 50 radially to the X1 axis. The elements 81 and 82 are for example smooth rings or bearings. This design with central bearing 80 is made possible by the use of a motor 20 with a relatively short length along the axis X1. Thus, the rotor 40 can be mounted cantilevered on the side of the rear end 53 of the shaft 50. This solution is enabled by the use of synchronous motor technology with rotor magnets 40. engine offers optimum performance over the entire speed range, as well as reduced weight and bulk.

FIG. 5 shows a centrifugal motor pump P2 with a closed rotor according to a second embodiment of the invention. Some components of the motor pump P2 are comparable to those of the motor pump P1 described above and, for the sake of simplification, bear the same reference numerals.

P2 motor pump comprises two bearings 8 and 9 disposed on either side of the rotor 40. The bearing 8 supports the current portion 51 of the shaft 50 between the rotor 40 and the wheel 60, while the bearing 9 supports the rear end 53 of the shaft 50. Each bearing 8 and 9 comprises a single element, respectively 81 and 91, supporting the shaft 50. For example, the elements 81 and 91 may be smooth rings or bearings. Each bearing 8 and 9 comprises a cylindrical wall, respectively 18 and 19, of the housing 10. Each of the elements 81 and 91 is mounted in the bore defined by one of the walls 18 and 19. The housing 10 comprises a cover 13 allowing to close the envelope 12 at the level of the bearing 9.

In Figure 6 is shown a wheel variant 60, designed to equip a pump P1 or P2 according to the invention.

The central portion 61 of the wheel 60 is shaped like a booster propeller, also called an inductor, designed to improve the suction capacity of the fluid F by the wheel 60.

In addition, the central portion 61 includes an extension of the blades 62 of the wheel 60, also making it possible to improve the suction capacity of the fluid F by the wheel 60.

In practice, the motor pump P1 / P2 may be shaped differently from Figures 3 to 6 without departing from the scope of the invention. Moreover, the technical characteristics of the various embodiments and variants mentioned above may be, in whole or in part, combined with one another. Thus, the P1 / P2 pump can be adapted in terms of cost, functionality and performance.

Claims

Motor pump (P1; P2) with a wet rotor, comprising:

a housing (10) including a body (1 1) and a motor casing (12); an electric motor (20) including a stator (30) and a rotor (40) disposed in the motor casing (12);

a shaft (50) which extends along a central axis (X1), which is integral with the rotor (40) in rotation about the central axis (X1), and which has a front end (52) located outside the motor casing (12) in the body (1 1) of the casing (10); and

a wheel (60) which is located at the front end (52) of the shaft (50), which is integral with the shaft (50) in rotation about the central axis (X1), and which has a hydraulic profile adapted to the displacement of a fluid (F) in the body (1 1);

wherein the rotor (40), the shaft (50) and the wheel (60) form a rotatable assembly (ER1; ER2);

and wherein within the rotary assembly (ER1; ER2), only the shaft (50) is supported by one or more bearings (80; 8,9), thereby guiding the rotating assembly in rotation ( ER1; ER2);

characterized in that the shaft (50) and the wheel (60) constitute at least in part a single piece (70).

Motor pump (P1; P2) according to claim 1, characterized in that the shaft (50) and the wheel (60) constitute integrally a single piece (70).

Motor pump (P1; P2) according to one of claims 1 or 2, characterized in that the wheel (60) comprises a central portion (61), which is located on the central axis (X1), belongs to the one-piece piece (70), and lacks a fastening system.

Motor pump (P1; P2) according to claim 3, characterized in that the central portion (61) forms a booster propeller.

5. Motor pump (P1; P2) according to one of claims 3 or 4, characterized in that the central portion (61) includes an extension of the blades (62) of the wheel (60). Motor pump (P1) according to one of claims 1 to 5, characterized in that it comprises a single bearing (80) which supports the shaft (50) radially to the central axis (X1) for rotating guide the rotary assembly (ER1), which is located between the rotor (40) and the wheel (60) along the central axis (X1).

Motor pump (P2) according to one of claims 1 to 5, characterized in that it comprises a front bearing (8) and a rear bearing (9) which support the shaft (50) radially to the central axis (X1 ) to guide in rotation the rotary assembly (ER2), the front bearing (8) being located between the rotor (40) and the wheel (60) along the central axis (X1).

Motor pump (P1; P2) according to one of the preceding claims, characterized in that the electric motor (20) is constructed according to synchronous motor technology with rotor magnets (40).

Motor pump (P1; P2) according to one of the preceding claims, characterized in that the stator (30), comprising an electromagnetic core (31) and a coil (32), has an inner surface entirely wrapped in a non-metallic material , facing the rotor (40) and in contact with the fluid (F) flowing in the motor casing (12).

10. Motor pump (P1; P2) according to claim 9, characterized in that the stator (30) is embedded in a sealed resin coating (33), at least along the inner surface.

1 1. Motor pump (P1; P2) according to one of the preceding claims, characterized in that the motor pump (P1; P2) is a centrifugal pump, the hydraulic profile of the wheel (60) being adapted to the energy transmission by centrifugation of the pump. fluid (F). 12. A method of manufacturing a motor pump (P1; P2) according to one of claims 1 to 1 1, characterized in that the shaft (50) and the wheel (60) are at least partly manufactured in the form of a one-piece piece (70), for example according to a sand molding technique, a metal mold or lost wax technique, sintering, welding, additive manufacturing, or a combination of several techniques.

13. A method of manufacturing a motor pump (P1; P2) according to claim 12, characterized in that it comprises an additive manufacturing operation of the one-piece piece (70).

14. A method of manufacturing a motor pump (P1; P2) according to claim 12, characterized in that it comprises an additive manufacturing operation of at least a portion of a mold including a cavity corresponding to the one-piece part ( 70), then an operation of manufacturing the one-piece piece (70) in this mold.