US20160341202A1 - Electric motor and electric pump - Google Patents

Abstract

An electric pump has a pump body, a pump magnet received in the pump body, an impeller received in the pump body and fixed to the pump magnet, and a disc type electric motor. The electric motor includes a stator, disc type coils fixed to a surface of the stator, a rotor rotatably positioned above the coils, and a circuit board electrically connected to the coils. The rotor has a rotor magnet positioned beneath the pump body and magnetically coupled to the pump magnet. When the coils are energized, an axial magnetic field is generated to drive the rotor and, through the magnetic coupling between the rotor magnet and the pump magnet, rotate the impeller.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. 201510253238.X filed in The People's Republic of China on May 18, 2015, the entire contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
• This invention relates to an electric pump, and in particular, to an electric pump having a disc type electric motor and to a disc type electric motor.
BACKGROUND OF THE INVENTION
• Electric pumps for home appliances, such as dish washing machines, generally adopt a direct current electric motor with a radial gap or an induction motor with a radial gap. However, these electric motors have a comparatively long axial dimension and a complicated structure.
SUMMARY OF THE INVENTION
• Hence there is a desire for an electric pump having a short axial dimension.
• Accordingly, in one aspect thereof, the present invention provides an electric pump, comprising: a pump body; a pump magnet rotatably disposed in the pump body; an impeller disposed in the pump body and fixed to the pump magnet; and a disc type electric motor positioned beneath the pump body for rotating the magnet and the impeller, the disc type electric motor comprising a stator and a rotor, the stator comprising: a stator core, a number of disc type coils fixed to a surface of the stator core, and a circuit board positioned on an end of the stator and electrically connected to the disc type coils, the rotor comprising a rotor magnet positioned between the disc type coils and the pump body, the magnet being positioned confronting the pump magnet to produce a magnetic coupling between the rotor magnet and the pump magnet, wherein when electrical power is applied to the circuit board, the disc type coils generate an axial magnetic field to drive the rotor, thereby rotating the pump magnet and the impeller.
• Preferably, a plurality of fasteners secure the disc type electric motor to the pump body.
• Preferably, spaced tabs extend radially from the stator, each tab has a through hole, the fasteners engage the through holes to secure the disc type electric motor to the pump body.
• Preferably, an iron sheet is fixed to the pump magnet, providing a flux return path.
• According to a second aspect, the present invention provides a disc type electric motor, having a stator and a rotor, the stator comprising: a stator core; a number of disc type coils fixed to a surface of the stator core; a circuit board positioned on an end of the stator core and electrically connected to the disc type coils, the rotor rotatably positioned above the disc type coils and comprising a rotor magnet; and wherein when the circuit board is energized, the disc type coils generate an axial magnetic field to rotate the rotor.
• Preferably, the stator has a plurality of grooves and through holes through which ends of windings of the disc type coils pass.
• Preferably, the stator core has a plurality of first through holes arranged in the circumferential direction, through which the windings of the disc type coils pass to reach a lower surface of the stator core.
• Preferably, the motor comprises a plurality of bobbins, a plurality of positioning members, and a plurality of second through holes formed in the stator core and arranged in the circumferential direction, wherein the disc type coils are wound around the bobbins, each bobbin defines a third through hole, and each positioning member extends through a respective third through hole and a respective second through hole to secure a respective bobbin to the stator core.
• Preferably, the rotor magnet is annular with a plurality of grooves formed in a radially inner surface and spaced in the circumferential direction, a solid glue is applied to the grooves to secure the rotor magnet to a shaft of the rotor.
• Preferably, the disc type electric motor further comprises a solid glue layer, the solid glue layer is applied on an lower surface of the stator core and covers exposed parts of the windings of the coils.
• According to a third aspect, the present invention provides an electric pump, comprising: a pump body; a pump magnet received in the pump body; an impeller received in the pump body and fixed to the pump magnet; a disc type electric motor for rotating the pump magnet and the impeller; and an iron sheet fixed between the pump magnet and the impeller.
• According to a fourth aspect, the present invention provides an electric pump, comprising: a pump body; an impeller received in the pump body; an electric motor for driving the impeller, wherein the electric motor is a disc type electric motor and drives the impeller through a magnetic coupling.
• Preferably, a pump magnet is fixed to the impeller within the pump body; and an iron sheet is fixed between the pump magnet and the impeller.
• Preferably, the disc type electric motor is an electric motor as defined in the second aspect above.
• Advantages of the present invention include providing an electric pump with short axial dimension, which meets the trend of miniaturization of home appliances. Further advantages of specific embodiments may be understood from the description of the preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
• A preferred embodiment of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below.
• FIG. 1 is a schematic view of an electric pump in accordance with a preferred embodiment of the invention;
• FIG. 2 is a sectional view of the electric pump ofFIG. 1;
• FIG. 3 is a view of an electric motor, being a part of the pump ofFIG. 1;
• FIG. 4 is a view of an electric motor according to a second embodiment;
• FIG. 5 illustrates the electric motor ofFIG. 4, with a rotor removed; and
• FIG. 6 illustrates the electric motor ofFIG. 3 or 4, viewed from another aspect.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• FIG. 1 is a schematic view of anelectric pump1 in accordance with a preferred embodiment of the invention.FIG. 2 is a sectional view of the pump. Thepump1 includes apump body10, apump magnet14 disposed in thepump body10, animpeller11 disposed in thepump body10 and fixed with thepump magnet14, and a disc typeelectric motor20 for rotating thepump magnet14 and theimpeller11 within thepump body10. In this embodiment, the disc typeelectric motor20 is a brushless electric motor. In other embodiments, the disc typeelectric motor20 may be a brush type electric motor.
• In this embodiment, thepump magnet14 and theimpeller11 are rotatably fixed to an inner surface of a bottom of thepump body10 via aspindle12 and a bearing (not shown), such that the impeller and pump magnet are able to rotate about the axis of the spindle within thepump body10. Thespindle12 may or may not be rotatable. Thepump10 includes awater inlet110 and awater outlet111.
• As shown inFIG. 3, the disc typeelectric motor20 includes arotor21 and astator25. The stator includes astator core255 and a number ofdisc type coils24 fixed to a surface of thestator core255. Acircuit board23 is fixed to thestator core255 and is electrically connected to thedisc type coils24. Therotor21 is positioned above thedisc type coils24, and is rotatably connected to thestator25 via ashaft27 and abearing250. In this embodiment, therotor21 has arotor magnet212. When thecircuit board23 is connected to an external power source and is powered on, thecoils24 are energized and generate an axial magnetic field, that causes therotor21 to rotate. In this embodiment, therotor21 is disc shaped and thestator core255 is a flat plate. Thestator25 and thecircuit board23 may be integrally formed.
• A plurality of spacedtabs26 extend outwardly in a radial direction from the stator. Eachtab26 has a throughhole22. Themotor20 is fixed to an external surface of a bottom of thepump body10 by a plurality of fasteners30 (as shown inFIG. 2) engaging in the throughholes22 of thetabs26. In this embodiment, thefasteners30 are screws. Threetabs26 andfasteners30 are used in this embodiment but the number may vary according to need. In other embodiments, thefastener30 may be fixed to the external surface of the bottom of thepump body10 by other means, such as welding.
• As shown inFIG. 4, therotor magnet212 is annular. A radially inner circumferential surface of the rotor magnet has a number ofinterleaved protrusions210 andgrooves211.Solid glue213 is applied into thegroove211 to secure theshaft27 to a middle of therotor magnet212. Theprotrusions210 are configured to generate a relative larger surface area for the glue to bond to the rotor magnet. In this embodiment, the main gradient of the solid glue is epoxy resin.
• As shown inFIG. 5 andFIG. 6, a plurality of spacedgrooves253 are defined at a radial outer surface of thestator25. An end of the windings of thecoils24 extends through arespective groove253 to a lower surface of the stator core.
• As shown inFIG. 6, thestator25 has a plurality of first throughholes251 and a plurality of second throughholes252 arranged in the circumferential direction. A circle on which the first throughholes251 are located and a circle on which the second through holes are located are concentric.
• The first throughholes251 allow the other end of the windings of the disc type coils24 to pass through thestator core255. The disc typeelectric motor20 further includes a plurality ofbobbins29 and a plurality ofpositioning members291. Eachbobbin29 defines a third throughhole290. Each positioningmember291 extends through a third throughhole290 and a second throughhole252 to secure the correspondingbobbin29 to the surface of thestator25. Eachcoil24 is wound around arespective bobbin29. In this embodiment, eachbobbin29 has a trapezoidal shape. Alternatively, the positioning members may be integrally formed with the bobbins.
• The disc typeelectric motor20 further includes asolid glue28. Thesolid glue28 is applied on the lower surface of thestator25, the outer surface of thestator25 and those parts of thedisc type coil24 that are exposed to air, thereby completely isolating the windings of thecoils24 from the external environment, reducing potential damage to thedisc type coil24.
• Furthermore, theelectric pump1 includes aniron sheet13 fixed above thepump magnet14. Theiron sheet13 provides a magnetic flux return path, to enhance the magnetic field intensity.
• When theelectric pump1 is used, electrical power is supplied to thecircuit board23, energizing thecoils24 to generate an axial magnetic field. The axial magnetic field drives therotor21. Rotation of therotor21 drives thepump magnet14 in thepump body10 causing theimpeller11 to rotate. At the same time, theiron sheet13 fixed above thepump magnet14, forms a magnetic flux return path, thereby enhancing the magnetic field intensity, and forming a better magnetic connection between the rotor magnet and the pump magnet, through which therotor21 drives theimpeller11.
• Further, the rotor of the disc typeelectric motor20 is not physically connected to thepump magnet14 in thepump body10 via a spindle or shaft, and does not extend into an inside of the pump body. Rather, the rotor of the disc typeelectric motor20 and theimpeller11 are located on opposite sides of a continuous bottom wall portion of the pump. Thus the motor is isolated from the working fluid of the pump and there are no seals that may fail leading to leakage of liquid from the pump and/or failure of the motor.
• In this embodiment of the invention, by adopting the disc type electric motor, the height of the pump can be kept small while eliminating the need for shaft seals and the like.
• In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item or feature but do not preclude the presence of additional items or features.
• It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.
• The embodiments described above are provided by way of example only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.

Claims (12)

1. An electric pump, comprising:

a pump body;

a pump magnet rotatably disposed in the pump body;

an impeller disposed in the pump body and fixed to the pump magnet; and

a disc type electric motor positioned beneath the pump body for rotating the magnet and the impeller, the disc type electric motor comprising a stator and a rotor, the stator comprising:

a stator core,

a number of disc type coils fixed to a surface of the stator core, and

a circuit board positioned on an end of the stator and electrically connected to the disc type coils,

the rotor comprising a rotor magnet positioned between the disc type coils and the pump body, the magnet being positioned confronting the pump magnet to produce a magnetic coupling between the rotor magnet and the pump magnet,

wherein when electrical power is applied to the circuit board, the disc type coils generate an axial magnetic field to drive the rotor, thereby rotating the pump magnet and the impeller.

2. The electric pump ofclaim 1, further comprising a plurality of fasteners securing the disc type electric motor to the pump body.

3. The electric pump ofclaim 2, wherein spaced tabs extend radially from the stator, each tab has a through hole, the fasteners engage the through holes to secure the disc type electric motor to the pump body.

4. The electric pump ofclaim 1, further comprising an iron sheet fixed to the pump magnet, providing a flux return path.

5. A disc type electric motor, having a stator and a rotor, the stator comprising:

a stator core;

a number of disc type coils fixed to a surface of the stator core;

a circuit board positioned on an end of the stator core and electrically connected to the disc type coils,

the rotor rotatably positioned above the disc type coils and comprising a rotor magnet; and

wherein when the circuit board is energized, the disc type coils generate an axial magnetic field to rotate the rotor.

6. The motor ofclaim 5, wherein the stator has a plurality of grooves and through holes through which ends of windings of the disc type coils pass.

7. The motor ofclaim 5, wherein the stator core has a plurality of first through holes arranged in the circumferential direction, through which the windings of the disc type coils pass to reach a lower surface of the stator core.

8. The motor ofclaim 5, further comprising a plurality of bobbins, a plurality of positioning members, and a plurality of second through holes formed in the stator core and arranged in the circumferential direction, wherein the disc type coils are wound around the bobbins, each bobbin defines a third through hole, and each positioning member extends through a respective third through hole and a respective second through hole to secure a respective bobbin to the stator core.

9. The motor ofclaim 5, wherein the rotor magnet is annular with a plurality of grooves formed in a radially inner surface and spaced in the circumferential direction, a solid glue is applied to the grooves to secure the rotor magnet to a shaft of the rotor.

10. The motor ofclaim 5, wherein the disc type electric motor further comprises a solid glue layer, the solid glue layer is applied on an lower surface of the stator core and covers exposed parts of the windings of the coils.

11. An electric pump, comprising:

a pump body;

a pump magnet received in the pump body;

an impeller received in the pump body and fixed to the pump magnet;

a disc type electric motor for rotating the pump magnet and the impeller; and

an iron sheet fixed between the pump magnet and the impeller.

12. The pump ofclaim 11, wherein the disc type electric motor has a stator and a rotor, the stator comprising:

a stator core;

a number of disc type coils fixed to a surface of the stator core;

a circuit board positioned on an end of the stator core and electrically connected to the disc type coils,

the rotor comprising a rotor magnet rotatably positioned above the disc type coils; and

wherein when the circuit board is energized, the disc type coils generate an axial magnetic field to rotate the rotor.

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