US20130064695A1

US20130064695A1 - Fluid pump having waterproof structure

Info

Publication number: US20130064695A1
Application number: US13/698,332
Authority: US
Inventors: Byoung Soo Kim
Original assignee: Amotech Co Ltd
Current assignee: Amotech Co Ltd
Priority date: 2010-05-19
Filing date: 2011-05-16
Publication date: 2013-03-14
Also published as: KR101237023B1; KR20110127311A; WO2011145844A3; WO2011145844A2

Abstract

Provided is a fluid pump including: first and second housings that are mutually coupled; a support, shaft that is fixed to the second housing; an impeller that is accommodated in the first housing to thus pump fluid; a stator that is fixed to the second housing; a first rotor that is placed inside the second housing, rotatably supported on the support shaft, and is placed facing one side of the stator; and a second rotor that is fixed to the impeller, rotatably supported on the support shaft, and is placed facing the other side of the stator. The fluid pump employs an axial type brushless direct-current (BLDC) motor as a drive motor for driving an impeller, to thus realize a slim structure, and is formed to have the stator of the motor buried in the housing, to thus improve waterproof performance of the motor.

Description

TECHNICAL FIELD

The present invention relates to a waterproof fluid pump that can fundamentally prevent fluid such as water from being introduced in the inside of a motor.

BACKGROUND ART

In general, a water pump motor is used to drive a water pump that is installed in a drain water tank of a washing machine or is used as a driving source of a water pump that is used for circulation of a coolant that cools an engine. A water pump equipped with the water pump motor works under an environment that the inside of the water pump always directly contacts water.
Thus, a motor pump having a mechanical seal structure or a canned motor pump having a canned cover structure for sealing a stator is used for the purpose of protecting a motor from water when the water of the inside of a water pump is drained to the outside of the water pump or in order to prevent failure of bearings or shortened life of belts due to leakage of a coolant.
U.S. Pat. No. 4,277,115 proposed the canned motor pump, in which a canned cover seals only a stator and thus a rotor soaks in water. Accordingly, durability of a bearing to support a rotational shaft is adversely affected. In addition, an optimal magnetic gap cannot be maintained because of a canned cover that is placed between the rotor and the stator, to thereby cause a low efficiency.
In addition, since the rotor soaks in water in the canned motor pump, rotation of the rotor is affected to thus decrease a motor efficiency.
Moreover, since a conventional motor pump has a structure that the axis of rotation of the impeller is integrally formed with the axis of rotation of the motor, a motor assembly and a pump assembly may not be independently assembled and tested, to thus cause a low assembly productivity problem.
In addition, when the canned cover for use in the canned motor pump is molded by using a PPS (PolyPhenylene Sulfide) material and then assembled with a stator, there is a problem that the canned cover is not easily combined with a stator core.
Furthermore, according to the conventional art, the outside of the stator employs a double sealing structure. Here, the outside of the stator is insert-molded by using BMC (Bulk Mould Compound) and is simultaneously sealed by a canned cover using a PPS sealing material, to thus cause a manufacturing cost to increase.

DISCLOSURE

Technical Problem

To solve the above problems or defects, it is an object of the present invention to provide a fluid pump that employs an axial type brushless direct-current (BLDC) motor as a drive motor for driving an impeller, to thus realize a slim structure.
It is another object of the present invention to provide a fluid pump that employs an axial type brushless direct-current (BLDC) motor that is a double rotor structure, to thus suppress axial vibration and fundamentally prevent water from being introduced into the interior of the motor.
It is still another object of the present invention to provide a fluid pump in which a coreless type stator and a support shaft are integrally formed in a pump housing, to thus omit a separate waterproof treatment, and to thereby enhance a motor efficiency by setting an optimal magnetic gap between a rotor and a stator in a drive motor.
It is yet another object of the present invention to provide a fluid pump that can seal a drive motor without an additional sealing device, to thus reduce a manufacturing cost.

Technical Solution

To accomplish the above and other objects of the present invention, according to an aspect of the present invention, there is provided a waterproof fluid pump comprising:
first and second housings that are mutually coupled;
a support shaft that is fixed to the second housing;
an impeller that is accommodated in the first housing to thus pump fluid;
a stator that is fixed to the second housing;
a first rotor that is placed inside the second housing, rotatably supported on the support shaft, and is placed facing one side of the stator; and
a second rotor that is fixed to the impeller, rotatably supported on the support shaft, and is placed facing the other side of the stator.
Preferably but not necessarily, the support shaft is integrally formed on an upper plate of the second housing by an insert-molding method, in which an upper side of the support shaft is located inside the first housing and a lower side thereof is located inside the second housing.
Preferably but not necessarily, a driver that applies a driving signal for the stator is accommodated inside the second housing.
Preferably but not necessarily, a stator is a coreless type.
Preferably but not necessarily, the stator is integrally fixed on an upper plate of the second housing by an insert-molding method.
Preferably but not necessarily, the first and second rotors comprise a number of magnets made of divided magnet pieces, or a ring shape magnet that is divisionally magnetized into an N-pole and an S-pole, alternately.
Preferably but not necessarily, the first and second rotors are disposed so that surfaces facing between the first and second rotors have opposite polarities.
Preferably but not necessarily, the first rotor comprises:
a rotor support that is rotatably supported on the support shaft that is placed inside the second housing;
a plurality of magnets that are fixed to the rotor support; and
a back yoke that is disposed on rear surfaces of the magnets.
Preferably but not necessarily, the second rotor comprises:
a rotor support that is rotatably supported on the support shaft that is placed inside the first housing and that is fixed to the impeller;
a plurality of magnets that are fixed to the rotor support; and
a back yoke that is disposed on rear surfaces of the magnets.
Preferably but not necessarily, the first and second rotors are rotatably supported on the support shaft by sleeve bearings, respectively.
According to another aspect of the present invention, there is also provided a fluid pump comprising:
an axial type motor comprising a stator that generates a rotating torque, and first and second rotors that are disposed in both sides of the stator;
a first housing in which an inlet and an outlet through which fluid flows in and out, respectively, and that accommodates the second rotor;
a second housing that accommodates the first rotor and on an upper plate of which the stator is integrally recessedly formed;
a support shaft that is disposed to penetrate the upper plate of the second housing, in which the first rotor is rotatably supported on an upper side of the support shaft and the second rotor is rotatably supported on a lower side thereof; and
an impeller that is accommodated in the first housing and is integrally formed with the first rotor to thus pump fluid.

Advantageous Effects

As described above, a fluid pump according to the present, invention employs an axial type brushless direct-current (BLDC) motor as a drive motor for driving an impeller, to thus realize a slim structure half a size when compared with a core type drive motor.
In addition, a fluid pump according to the present invention employs an axial type brushless direct-current (BLDC) motor that is a double rotor structure, to thus suppress axial vibration.
In addition, a fluid pump according to the present invention is configured to have a coreless type stator and a support shaft that are integrally formed in a pump housing, in which a first rotor is integrally formed with an impeller and a second rotor is disposed outside the pump housing, to thereby block water from being introduced into a drive motor.
Moreover, a fluid pump according to the present invention is configured, to have a coreless type stator and a support shaft that are integrally formed in a pump housing, to thus omit a separate waterproof treatment, and to thereby enhance a motor efficiency by setting an optimal magnetic gap between a rotor and a stator in a drive motor.
In addition, the present invention can seal a motor without an additional waterproof structure such as a sealing canned cover, to thus reduce a manufacturing cost.

DESCRIPTION OF DRAWINGS

FIG. 1 is an axial cross-sectional view illustrating a fluid pump according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a coil of a stator and magnets of a rotor in a motor employed in the fluid pump of FIG. 1.

FIG. 3 is a sectional view illustrating a stator in the motor of FIG. 1.

FIG. 4 is a plan view illustrating a rotor in the motor of FIG. 1.

BEST MODE

Hereinafter, a fluid pump according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying FIGS. 1 to 4.
Referring to FIGS. 1 to 4, a fluid pump according to an embodiment of the present invention, largely includes: a pump housing 10, a motor 1, and an impeller 43.
The pump housing 10 includes: a first housing 15 in which an inlet 15 a through which fluid flows in and an outlet 15 b through which the fluid is discharged; and a second housing 14 that is sealably mounted on an opened bottom of the first housing 15.
A motor 1 and a driver 36 for driving the motor 1 are housed inside the second housing 14, and a cover 11 is sealably coupled to an opened bottom of the second housing 14.
At least three fixing extension units 11 b and 14 b are protruded between the cover 11 and the second housing 12, in which fixing screws or fixing bolts are combined into fixing holes. In addition, a cylindrical protrusion 11 a is protruded on top of the cover 11, and a sealing O-ring 35 b is inserted between the outer circumferential surface of the cylindrical protrusion 11 a facing the second housing 14 and the inner circumferential surface of the second housing 14.
At least three fixing extension units 14 c and 15 d are protruded for mutual coupling between the second housing 14 and the first housing 15, in which fixing screws or fixing bolts are combined with fastening holes, respectively. In addition, a sealing O-ring 35 b is inserted into a recess formed on the outer circumferential surface of the second housing 14, to thus seal between the first housing 15 and the second housing 14.
The inlet 15 a through which fluid flows in is formed at the center of the upper side of the first housing 15 and the outlet 15 b through which the pumped fluid is discharged is formed in the side surface of the first housing 15. The impeller 43 is placed along a fluid flow passage P that is formed between the inlet 15 a and the outlet 15 b.
The first housing 15 is formed so that the impeller 43 is disposed along a fluid flow path P and an opened bottom of the first housing is expanded to ensure a wider space than the inlet 15 a.
An insertion unit 14 d that is inserted into the inner surface of the lower side of the first housing 15 is formed on the upper side of the second housing 14.
The impeller 43 is formed to have a circular plate shaped body 43 a and a number of wings 43 b that are radially formed on top of the circular plate shaped body 43 a, so that fluid such as water that is introduced through the inlet 15 a is discharged through the outlet 15 b that is disposed at the side surface of the fluid pump.
The support shaft 27 is buried into and integrally formed with an upper plate 14 a of the second housing 14 when the support shaft 27 is insert-molded in order to mold the second housing 14.
Thus, since the support shaft 27 it is integrally formed with the second housing 14, the fluid can be blocked from being introduced into the internal space of the second housing 14.
The lower end of the support shaft 27 is inserted into the pressing unit lie that is formed at the center of the cover 11, and a stopper 44 for preventing secession of the impeller 43 is coupled on top of the support shaft 27.
Meanwhile, the fluid pump according to the present invention employs an axial type brushless direct-current (BLDC) motor 1 including a coreless type stator 26, and double rotors 20 and 30 that are symmetrically disposed at both sides of the stator 26, as a driving unit for rotationally driving the impeller 43.
As shown in FIGS. 2 and 3. for example, six coils 26 b that are respectively wound around six parallelogram rectangular-shaped bobbins 26 a are buried into the upper plate 14 a of the second housing 14, when the second housing 14 is molded, and thus the coreless type stator 26 is integrated with the upper plate 14 a of the second housing 14 in an insert-molding method.
In this case, the six coils 26 b may be molded by a resin insulating material in a state where the six coils 26 b are wired with a secondary PCB (Printed Circuit Board), in order to facilitate interconnection between the coils 26 b.
The coils 26 b of the stator 26 are wound around the bobbin 26 a after three coils are divided into six coils, for example, in a three-phase driving mode, and are wired with the secondary PCB in a Y-connection manner. In a two-phase driving mode, after two coils are divided into eight coils, the coils 26 b of the stator 26 are wound around the bobbin 26 a and are wired in a serial fashion with the secondary PCB.
The coils 26 b form the stator 26 at a state where exposed portions of the coils are sealed with a resin insulating material, to thus ensure insulation between the coils 26 b wound around the bobbin 26 a, and to thereby provide excellent moisture-proof performance, vibration absorption, and corrosion resistance.
A throughhole 14 e through which the support shaft 27 passes is formed in the upper plate 14 a of the second housing 14, and the support shaft 27 is integrally fixed to the second housing 14 in an insert-molding method, to thus block fluid from leaking through the throughhole 14 e.
The double rotors 20 and 30 include a first rotor 20 and a second rotor 30 that are symmetrically disposed with an air gap at both sides of the stator 26. The first rotor 20 is positioned inside the second housing 14 and the second rotor 30 is positioned inside the first housing 15. The first and second rotors 20 and 30 are rotatably supported on the support shaft 27, respectively.
A first sleeve bearing 34 a is placed between the first rotor 20 and the support shaft 27 and a second sleeve bearing 34 b is placed between the second rotor 30 and the support shaft 27.
The first sleeve bearing 34 a and the second sleeve bearing 34 b are preferably oilless bearings such as carbon bearings and plastic bearings considering contact with he fluid.
The first rotor 20 includes: a plurality of magnets 22 that are spaced at a predetermined distance apart from one side of the stator 26 and are disposed in parallel with the stator 26; a back yoke 21 that is disposed on rear surfaces of the magnets 22 to thus form a magnetic circuit: and a rotor support 23 that makes the magnets 22 and the back yoke 21 integrally fixed, and that is rotatably supported on the support shaft 27.
Here, the magnets 22 and the back yoke 21 are integrally formed with the rotor support 23 in an insert-molding formed.
The second rotor 30 includes: a plurality of magnets 32 that, are spaced at a predetermined distance apart from the other side of the stator 26 and are disposed in parallel with the stator 26; a back yoke 31 that is disposed on rear surfaces of the magnets 32 to thus form a magnetic circuit; and a rotor support 33 that makes the magnets 32 and the back yoke 31 integrally fixed, and that is rotatably supported on the support shaft 27.
Here, the magnets 32 and the back yoke 31 are integrally formed with the rotor support 33 in an insert-molding formed.
As shown in FIG. 2, according to relationship between mutual positions of the magnets 22 and 32 and the coils 26 b of the stator 26, the disc-shaped magnets 22 and 32 are disposed in opposition to the bobbin 26 a, that is, the rectangular-shaped bobbin coils 26 b.
The stator 26 includes six coils 26 b. and the first rotor 20 and the second rotor 30 have a structure that eight N-pole and S- pole magnets 22 and 32 are alternately arranged, respectively.
In this case, as shown in FIG. 4, the first rotor 20 and the second rotor 30 may be implemented by using a number of N-pole and S-pole divided magnet pieces, or a ring-shaped magnet, that is divisionally magnetized into an N-pole and an S-pole alternately.
A number of the stator coils 26 b are buried into a center of an upper plate 14 a of the second housing 14 and thus the stator 26 is integrally formed with the second housing 14, when the stator 26 is insert-molded in order to mold the second housing 14.
As described above, since the stator 26 is integrally formed inside the second housing 14 in an insert-molding method, water can be fundamentally blocked from being introduced into the stator 26.
The stator 26 receives driving signals for the stator coils 26 b from a driver 36 that is housed in the second housing 14.
An operation of the fluid pump according to the present invention configured as described above will be described as follows.
When a driving current is applied to the coils 26 b of the motor 1 from the driver 36, a magnetic field is formed in a predeterminedly set direction. Here, when the magnets 22 and 32 of the first rotor 20 and the second rotor 30 are arranged in opposite polarities to each other, an identical repulsive force or attraction force is generated between the magnets 22 and 32 of the first rotor 20 and the second rotor 30 and the coils 26 b, respectively.
Therefore, the repulsive force and the attraction force between the magnets 22 and 32 and the coils 26 b are generated in opposite directions and thus cancelled each other, to thus maintain axial vibration at minimum and rotate the rotor 20 and the second rotor 30 around the support shaft 27. The impeller 43 integrally formed with the second rotor 30 is rotated, due to the rotation of the first rotor 20 and the second rotor 30. As a result, fluid introduced into the inlet 15 a is pumped and then the pumped fluid is discharged through the outlet 15 b.
The fluid pump according to the embodiment of the present invention employs an axial type coreless type BLDC motor as the motor 1 for driving the impeller 43, and realizes a slim structure that size of the motor is reduced into about a half and weight thereof is reduced into about one third when compared with a general core type motor.
In addition, the fluid pump according to the embodiment of the present invention is implemented by integrating the coreless type stator 26 and the support shaft 27 with the second housing 14 of the pump housing 10, while employing a double rotor type motor for use in an axial type coreless type BLDC motor, to thereby realize a perfect waterproof performance for the motor 1.
Moreover, the fluid pump according to the embodiment of the present invention is implemented by integrating the coreless type stator 26 and the support shaft 27 with the second housing 14 of the pump housing 10, to thus omit a separate waterproof treatment as in a conventional sealing canned cover, and to thereby enhance a motor efficiency and save a manufacturing cost, by setting an optimal magnetic gap between each of the first and second rotors 20 and 30 and the stator 26 in the motor 1.
In addition, the fluid pump according to the embodiment of the present invention may minimize components necessary to drive and support the impeller 43, to thus achieve cost savings and improved durability.
In the above-described embodiment, when the axial type BLDC motor is employed as the drive motor 1 for driving the impeller 43, the coreless type stator has been used in order to achieve a slim structure, but it is possible to use a core type stator.
In the above-described example, the case that the coils 26 b are wound around the bobbin 26 a in the coreless type stator has been described, but it is possible to use bobbineless type coils in order to achieve a more slimmer structure.
As described above, the present invention has been described with respect to particularly preferred embodiments. However, the present invention is not limited to the above embodiments, and it is possible for one who has an ordinary skill in the art to make various modifications and variations, without departing off the spirit of the present invention. Thus, the protective scope of the present invention is not defined within the detailed description thereof but is defined by the claims to be described later and the technical spirit of the present invention.

INDUSTRIAL APPLICABILITY

The fluid pump according to the embodiment of the present invention employs a structure that a motor that generates a rotating torque and an impeller that pumps fluid are isolated from each other, and the rotating torque of the motor is delivered to the impeller by using a magnetic force, thereby fundamentally waterproofing the motor, and thus may be applied to a fluid pump that needs sealing of a motor as in a water pump or fuel pump.

Claims

1. A fluid pump comprising:

first and second housings that are mutually coupled;

a support shaft that is fixed to the second housing;

an impeller that is accommodated in the first housing to thus pump fluid;

a stator that is fixed to the second housing;

a first rotor that is placed inside the second housing, rotatably supported on the support shaft, and is placed facing one side of the stator; and

a second rotor that is fixed to the impeller, rotatably supported on the support shaft, and is placed facing the other side of the stator.

2. The fluid pump according to claim 1, wherein the support shaft is integrally formed on an upper plate of the second housing by an insert-molding method, in which an upper side of the support shaft is located inside the first housing and a lower side thereof is located inside the second housing.

3. The fluid pump according to claim 1, wherein a driver that applies a driving signal for the stator is accommodated inside the second housing.

4. The fluid pump according to claim 1, wherein a stator is a coreless type.

5. The fluid pump according to claim 1, wherein the stator is integrally fixed on an upper plate of the second housing by an insert-molding method.

6. The fluid pump according to claim 1, wherein the first and second rotors comprise a number of magnets made of divided magnet pieces, or a ring shape magnet that is divisionally magnetized into an N-pole and an S-pole, alternately.

7. The fluid pump according to claim 1, wherein the first and second rotors are disposed so that surfaces facing between the first and second rotors have opposite polarities.

8. The fluid pump according to claim 1, wherein the first rotor comprises:

a rotor support that is rotatably supported on the support shaft that is placed inside the second housing;

a plurality of magnets that are fixed to the rotor support; and

a back yoke that is disposed on rear surfaces of the magnets.

9. The fluid pump according to claim 1, wherein the second rotor comprises:

a rotor support that is rotatably supported on the support shaft that is placed inside the first housing and that is fixed to the impeller;

a plurality of magnets that are fixed to the rotor support; and

a back yoke that is disposed on rear surfaces of the magnets.

10. The fluid pump according to claim 1, wherein the first and second rotors are rotatably supported on the support shaft by sleeve bearings, respectively.

11. A fluid pump comprising:

an axial type motor comprising a stator that generates a rotating torque, and first and second rotors that are disposed in both sides of the stator;

a first housing in which an inlet and an outlet through which fluid flows in and out, respectively, and that accommodates the second rotor;

a second housing that accommodates the first rotor and on an upper plate of which the stator is integrally recessedly formed;

a support shaft that is disposed to penetrate the upper plate of the second housing, in which the first rotor is rotatably supported on an upper side of the support shaft and the second rotor is rotatably supported on a lower side thereof; and

an impeller that is accommodated in the first housing and is integrally formed with the first rotor to thus pump fluid.