WO2018197517A1 - Motorised pump with an embedded rotor - Google Patents

Abstract

The present invention relates to a motorised pump (1) with an embedded rotor, comprising: a casing (10) including a body (11) and a motor jacket (12), a synchronous electric motor (20) that is arranged in the motor jacket (12) and includes a stator (30) and a magnet rotor (40), a shaft (50) that extends along a central axis (X1), and a wheel (60) that has a hydraulic profile adapted for the movement of a fluid (F) in the body (11), the rotor (40), the shaft (50) and the wheel (60) forming a rotary assembly (ER1) freely rotating about the central axis (X1), the stator (30) including a magnetic core, a coil (32) and an encapsulation (34), in which the coil (32) and the magnetic core are embedded, a magnetic gap (22) being radially defined between the coil (32) and the magnets (42), the encapsulation (34) comprising an annular part (35) that surrounds the rotor (40) and a bottom (36) that passes through the central axis (X1), the bottom (36) of the encapsulation (34) being in the shape of a convex bell.

Description

 Motor pump with wet rotor

The present invention relates to a motor pump with a drowned rotor.

 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. This rotating assembly is supported by two bearings. The wheel is attached to the front end of the shaft, located outside the motor casing.

Another example of a motor-driven motor pump is known from DE20007099U 1. The stator comprises an encapsulation constituted by a coating and a sheath. This sheath has a cylindrical portion and a thin bottom, in contact with the fluid. This motor pump has a complex structure, with many parts interposed between the body and the engine casing constituting the housing, the rotor support shaft and the coating of the rotor. Another example is known from WO02 / 38964. However, the motor casing and the encapsulation of the stator are one and the same piece. In addition, the bottom of the encapsulation comprises a protruding element constituting a bearing support of the shaft. This element may be integral with the bottom of the encapsulation (Figure 1), or mounted in a hole formed in the bottom of the encapsulation (Figure 3).

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

To this end, the subject of the present invention is a motor-driven pump, comprising: a casing including a body and a motor casing, a synchronous electric motor which is arranged in the motor casing and which includes a stator and a magnet rotor , a shaft that extends along a central axis, and a wheel that has a profile hydraulic fluid adapted to the movement of a fluid in the body; the rotor, the shaft and the wheel forming a rotating assembly rotatable around the central axis; the stator including a coil inserted into a magnetic core, and an encapsulation in which the coil and the magnetic core are embedded; a magnetic gap being defined radially between the magnetic core and the magnets; encapsulating the stator comprising an annular portion which surrounds the rotor and a bottom which passes through the central axis; characterized in that the bottom of the encapsulation has a domed bell shape.

Thus, the motor pump according to the invention offers many advantages.

 The bottom of the domed bell-shaped encapsulation provides better strength and pressure. Also, with its large thickness, the bottom allows a better heat exchange with the outside on the back of the motor pump.

 Thanks to the flooded rotor, the motor pump has an absolute seal, high reliability and low maintenance. 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 particular, the large air gap makes it possible to use a non-metallic encapsulation for the stator. This encapsulation advantageously provides four functions: sealing, thermal diffusion, mechanical resistance and electrical insulation.

 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 features of the invention, taken separately or in combination:

 - The annular portion has an internal non-metallic surface resistant to abrasion.

- Opposite the wheel, a rear wall of the motor casing has an outlet opening of the electrical son of the stator, said son extending in the bottom of the encapsulation and out of the motor casing by the opening in a space of smaller diameter than the outer diameter of the coil.

- The output opening of the stator wires is formed in the rear wall at the central axis. - The bottom of the encapsulation is housed in the exit opening of the son.

 - The bottom of the encapsulation is extended in a housing encapsulating all or part of one or more components.

 - The ratio between the thickness of the magnetic gap defined radially to the central axis, and the thickness of a mechanical gap defined radially between the encapsulation of the stator and a rotor encapsulation, is greater than 2, preferably greater than 3.

 - The bottom of the encapsulation has a minimum thickness defined parallel to the central axis, the coil has a thickness defined radially to the central axis, the ratio between the minimum thickness of the bottom of the encapsulation and the thickness of the winding is greater than 0.5, preferably greater than 1.

 - The encapsulation is in resin.

 - The encapsulation is made of composite material, including one or more reinforcements.

Encapsulation is made of a composite material comprising one or more reinforcements consisting of fiberglass fabrics and a resin in which the reinforcement and the electromagnetic core and the coil are embedded;

 - The resin is an epoxy resin.

 - The annular portion has an inner surface formed by the resin of the encapsulation, and the reinforcement extends all around the central axis and the inner surface, between the inner surface and the coil.

 - The motor casing also has a domed bell shape marrying the bottom of the encapsulation.

 - The motor pump includes a bearing supporting the rotating assembly.

 The bearing comprises a piece of complex shape arranged in tight connection with the encapsulation.

 - The piece of complex shape is also arranged in sealed connection with the wheel.

 - The piece of complex shape is fixed between the body and the motor casing, in sealed connection with the body and the motor casing

 - Within the rotary assembly, only the shaft is supported by one or more bearings, thus ensuring the rotational guidance of the rotary assembly.

 - The motor pump comprises a single central bearing supporting the shaft.

 - The encapsulation is in contact only with the motor casing and the piece of complex shape of the bearing.

 - The rotor overlaps the bearing radially to the central axis.

- The shaft and the wheel are at least partly a single piece. The invention will be better understood on reading the description which follows, given solely by way of nonlimiting example and with reference to the appended drawings in which:

 Figure 1 is a rear view of a pump according to the invention;

 Figure 2 is a longitudinal section in the plane II-II in Figure 1;

 Figure 3 is a section similar to Figure 2, showing only the motor casing, the encapsulation of the stator, and the main part of the bearing;

 Figure 4 is an enlarged view of detail IV in Figure 2;

 Figure 5 is an enlarged view of detail IV in Figure 2;

 Figure 6 is a section similar to Figure 2 showing only the shaft and the wheel forming a single piece.

FIGS. 1 to 6 show a centrifugal motor pump 1 with a drowned rotor according to the invention.

The motor pump 1 comprises a housing 10, a synchronous electric motor 20, 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 casing 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 1.

 The body 1 1 has an inlet opening 13, an outlet opening 14, and feet 15. The structure of the body January 1 is not described in more detail for the sake of simplification.

 The casing 12 comprises an axial central wall 16, a radial front flange 17 and a radial rear wall 18. The wall 16 has a cylindrical tubular shape, the flange 17 has a flat annular shape, and the wall 18 has a flat annular shape . The flange 17 makes it possible to assemble the motor casing 12 with the body 1 1 and the bearing 80. The walls 16 and 18 delimit a compartment 160 receiving the stator 30 and the rotor 40. The wall 18 comprises an outlet opening 182 of the electrical son of the stator 30 (these son not being represented for the sake of simplification). The opening 182 is centered on the axis X1. Alternatively, the opening 182 may be offset radially to the axis X1.

The housing 10 also has a polygonal rear wall 19, which extends rearwardly from the wall 18 and defines a compartment 190. The compartments 160 and 190 are in communication via the opening 182 for passage of the son. A component of connection 191 is housed in the compartment 190 (or more components). The compartment 190 has an upper opening 192 and an axial opening 193 closed by a plate 200. The opening 192 has dimensions comparable to the opening 182, while the opening 193 has larger dimensions to allow access to the compartment 190 when the plate 200 is removed. Two handling rings 195 are anchored in the wall 19, on either side of the opening 193.

The stator 30 comprises an electromagnetic core (not shown for purposes of simplification), a winding 32, and an encapsulation 34. The core and the winding 32 are embedded in the encapsulation 34, thereby sealing the stator 30.

 Within the motor 20, a magnetic gap 22 is defined radially between the stator 30 and the rotor 40, more precisely between the magnetic core and the magnets 42. A mechanical gap 23 is defined between the encapsulation 34 of the stator 30 and the encapsulation (for example a metal jacket) of the magnets 42 of the rotor 40.

 Encapsulation is distinct from the motor envelope. This makes it possible to manufacture these two parts in different materials, for example a metal envelope 12 and a resin encapsulation 34. In addition, this facilitates the manufacture and assembly of the motor pump 1.

 The encapsulation 34 extends all along the stator 30, at the magnetic gap 22. The stator 30 is devoid of metal jacket. By using encapsulation 34 instead of the metal jacket of the stator 30, the eddy current losses are suppressed.

 The encapsulation 34 comprises an annular portion 35 and a bottom 36. The annular portion 35 is centered on the axis X1 and surrounds the rotor 40. The electromagnetic core and the coil 32 are embedded in this annular portion 35. The annular portion 35 The annular portion 35 has a cylindrical internal surface 37 in contact with the fluid, surrounding the rotor 40. The surface 37 is non-metallic and resistant to corrosion and abrasion.

 The bottom 36 extends transversely to the axis X1 and closes the encapsulation 34 at the rear wall 18 of the motor casing 12. The bottom 36 has an inner surface 38 concave and smooth in contact with the fluid, making facing the rotor 40.

According to the invention, the bottom 36 of the encapsulation 34 has a domed bell shape. The bottom 36 has a variable thickness defined parallel to the axis X1, important in its center and even more important in the angles connecting the bottom 36 to the part The inner surface 38 of the bottom 36 has a decreasing diameter from the annular portion 35 to the central axis X1.

 Thus, the bottom 36 provides a high mechanical strength and under pressure. Also, given its large thickness, especially in the angles connecting it to the annular portion 35, the bottom 36 allows good heat exchange with the outside of the motor pump 1.

As shown in Figure 3, the coil 32 has a thickness E32 defined radially to the axis X1 The bottom 36 has a minimum thickness E36, defined parallel to the axis X1, bordering the opening 182.

 The ratio between the thickness of the magnetic gap 22 and the thickness of the mechanical air gap 23 is greater than 2, preferably greater than 3. The ratio between the minimum thickness E36 and the thickness E32 of the winding 32 is greater than 1.

 Thus, the encapsulation 34 has a large thickness, both at the annular portion 35 and the bottom 36, and therefore good mechanical strength under pressure, and a good seal.

The encapsulation 34 may be of polymer resin, or of composite material comprising a polymer resin. Preferably, the resin is an epoxy resin (epoxy polymer).

 According to an advantageous embodiment, the encapsulation 34 is made of a composite material comprising one or more reinforcements (s) made of fiberglass fabric, and a resin in which the reinforcement (s) are embedded, the electromagnetic core and the coil 32. Preferably, the inner surface 37 of the annular portion 35 is formed by the resin of the encapsulation 34, while the reinforcement extends all around the central axis X1 and therefore the surface 37, between this surface 37 and the coil 32.

 According to another embodiment, the encapsulation 34 may comprise a sheath forming the inner surface 37 of the annular portion 35. This sheath may be fixed to the resin constituting the rest of the encapsulation 34. This sheath may be of any material non metallic ...

 Whatever the embodiment, the annular portion 35 thus has a satisfactory seal and mechanical strength of the internal side in contact with the fluid flowing in the compartment 160.

Advantageously, the bottom 36 consists of a single layer of resin. In the example of the figures, the motor casing 12 also has a domed bell shape conforming to the bottom 36 of the encapsulation 34, with the angle of the casing 12 which is rounded between the walls 16 and 18. This improves still the mechanical and pressure resistance of the motor pump 1.

 The electrical wires of the stator 40 extend from the winding 32 to the opening 182, being embedded in the annular portion 35 and then in the bottom 36 of the encapsulation 34. The wires emerge from the motor casing 12 through the opening 182 at the axis X1. If the opening 182 is offset radially with respect to the axis X1, the wires leave the motor casing 12 through the opening 182 in a space of smaller diameter than the outer diameter of the coil 32. The bottom 36 of the encapsulation 34 is housed in the exit opening 182 of the son.

Preferably, 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. One or more other parts of the shaft 50 and / or the wheel 60 may be formed by one or more different parts of the part 70.

 Still more preferably, as 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. These are formed of no other room 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.

 This offers responsiveness and freedom for the design of geometric shapes to improve the performance of the motor pump 1. In particular, great freedom of design is offered at the central portion of the wheel 60. This also improves the NPSH characterizing the suction performance of the motor pump 1.

The rotor 40 and the part 70 form a rotary assembly ER1, rotatable about the axis X1, within the motor pump 1. The shaft 50 extends along the axis X1, with a running portion 51 connecting a front end 52 and a rear end 53. The running portion 51 extends between the 1 1 body and the motor casing 12. The shaft 50 is supported by the bearing 80 in its current portion 51. The front end 52 is located outside the motor casing 12, in the body January 1. The rear end 53 is located in the motor casing 12. The rotor 40 is secured to the shaft 50 at its rear end 53, by any known means. In the example of the figures, the rotor 40 is secured to the shaft 50 in rotation by a key and axially by a nut, bearing washers and a shoulder formed on the shaft 50.

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 precisely the motor pump 1 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 motor pump 1. 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 from the wheel 60 to the shaft 50, for example of the screw or screen type, as in the state of the art. This provides greater design freedom at this central portion 61.

 In the example of the figures, 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.

The part 70 comprises a central channel 72, which opens along the axis X1 in the central portion 61 of the wheel 60 and at the rear end 53 of the shaft 50. This channel 72 allows the flow of fluid F between the body 1 1 and the motor casing 12.

The bearing 80 supports the rotary assembly ER1. 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. Advantageously, 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 includes a complex shaped part 82 and a bearing device 84. The bearing device 84 is supported by the workpiece 82 and supports the running portion 51 of the shaft 50. The bearing device 84 includes plain bushings 86. , bearings, or any other means adapted to support the shaft 50 movable in rotation about the axis X1.

 As shown in FIGS. 3 and 4, the piece 82 comprises three tubular portions 821, 823 and 825, and three radial portions 822, 824 and 826. The inner portion 821 comprises bores of different diameters, receiving the constituent elements of the bearing device. 84. The portion 822 connects the portions 821 and 823, and has fluid passage holes. The portion 823 is housed in a bore of the annular portion 35 of the encapsulation 34, and comprises an annular groove receiving a seal bearing against the encapsulation 34. The portion 824 connects the portions 823 and 825. The portion 825 is housed in the bore defined by the wall 16 of the motor encapsulation 12, for centering the workpiece 82 and therefore the bearing 80 as a whole. The portion 826 is disposed in abutment against the collar 17 of the motor encapsulation 12. The portion 826 comprises an annular groove receiving a seal bearing against the collar 17.

 The piece 82 is arranged in tight connection with the body 1 1, the motor envelope

12, the encapsulation 34 and the wheel 60, thanks to the aforementioned seals and other additional seals.

At this stage, it is noted that the encapsulation 34 is in contact only with the motor casing 12, the part 82, and the seal disposed in the portion 823 of the part 82. This makes it possible to ensure that the liquid may not slip into any gaps between the envelope 12 and the encapsulation 34 for a perfect seal. In practice, the synchronous motor 20 offers optimal performance over the entire speed range, as well as a reduced weight and bulk.

In addition, the use of the synchronous motor technology 20, with magnets 42 to the rotor 40, makes it possible to design the motor pump 1 with a relatively short motor length along the axis X1. Thus, this makes it possible to design the motor pump 1 with central bearing 80, and thus to mount the rotor 40 cantilevered on the side of the rear end 53 of the shaft 50. The rotor 40 overlaps the bearing 80 radially to the X1 axis, plus precisely a portion of the portion 821 and elements of the bearing device 84 housed therein. The size of the motor pump 1 is greatly reduced.

Furthermore, the motor pump 1 may be shaped differently from Figures 1 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 motor pump 1 can be adapted in terms of cost, functionality and performance.

Claims

Motor pump (1) with a drowned rotor, comprising:  a casing (10) including a body (1 1) and a motor casing (12), a synchronous electric motor (20) which is arranged in the motor casing (12) and which includes a stator (30) and a rotor ( 40) with magnets (42),  a shaft (50) extending along a central axis (X1), and  a wheel (60) having a hydraulic profile adapted to the displacement of a fluid (F) in the body (1 1); the rotor (40), the shaft (50) and the wheel (60) forming a rotatable assembly (ER1) rotatable about the central axis (X1); the stator (30) including a coil (32) inserted into an electromagnetic core, and an encapsulation (34) in which the electromagnetic core and the coil (32) are embedded; a magnetic gap (22) being defined radially between the electromagnetic core and the magnets (42); encapsulation (34) having an annular portion (35) surrounding the rotor (40) and a bottom (36) extending through the central axis (X1); characterized in that the bottom (36) of the encapsulation (34) has a domed bell shape. Motor pump (1) according to claim 1, characterized in that the annular portion (35) has an internal surface (37) non-metal resistant to abrasion. Motor pump (1) according to one of the preceding claims, characterized in that opposite the wheel (60), a rear wall (18) of the motor casing (12) has an outlet opening (182) electrical wires of the stator (20), said wires extending in the bottom (36) of the encapsulation (34) and coming out of the motor casing (12) through the opening (182) in a space of smaller diameter to the outer diameter of the coil (32). Motor pump (1) according to claim 3, characterized in that the outlet opening (182) of the son of the stator (20) is formed in the rear wall (18) at the central axis (X1). Motor pump (1) according to one of claims 3 or 4, characterized in that the bottom (36) of the encapsulation (34) is housed in the opening (182) output son. 6. Motor pump (1) according to one of claims 3, 4 or 5, characterized in that the bottom (36) of the encapsulation (34) is extended in a housing (190) encapsulating all or part of one or several components (191). 7. Motor pump (1) according to one of the preceding claims, characterized in that the ratio between the thickness of the magnetic gap defined radially to the central axis (X1), and the thickness of a defined mechanical gap radially between the encapsulation (34) of the stator (30) and an encapsulation of the rotor (40) is greater than 2, preferably greater than 3. 8. Motor pump (1) according to one of the preceding claims, characterized in that the bottom (36) of the encapsulation (34) has a minimum thickness (E36) defined parallel to the central axis (X1), the winding (32) has a thickness (E32) defined radially to the central axis (X1), the ratio between the minimum thickness (E36) of the bottom (36) of the encapsulation (34) and the thickness (E32) of the coil (32) is greater than 0.5, preferably greater than 1. 9. Motor pump (1) according to one of the preceding claims, characterized in that the encapsulation (34) is made of composite material including one or more reinforcements. 10. Motor pump (1) according to claim 9, characterized in that the encapsulation (34) is of composite material comprising one or reinforcement made of fiberglass fabric and a resin in which are embedded the reinforcement and the electromagnetic core and the winding (32). 1 1. Motor pump (1) according to claim 10, characterized in that the resin is an epoxy resin. 12. Motor pump (1) according to one of claims 9 or 10, characterized in that the annular portion (35) has an inner surface (37) formed by the resin of the encapsulation (34), and in that the reinforcement extends all around the central axis (X1) and the inner surface (37), between the inner surface (37) and the coil (32). 13. Motor pump (1) according to one of the preceding claims, characterized in that the motor casing (12) also has a domed bell shape conforming to the bottom (36) of the encapsulation (34). 14. Motor pump (1) according to one of the preceding claims, characterized in that it comprises a bearing (80) supporting the rotary assembly (ER1), the bearing (80) having a piece (82) of complex shape arranged in tight connection with the encapsulation (34). 15. Motor pump (1) according to claim 14, characterized in that the encapsulation (34) is in contact only with the motor casing (12) and the piece (82) of complex shape of the bearing (80). 16. Motor pump (1) according to one of the preceding claims, characterized in that it comprises a bearing (80) supporting the rotary assembly (ER1), the rotor (40) overlapping the bearing (80) radially to the central axis (X1).