Brushless DC motor in washing machine
Brushless motor in a washing machine including a stator having a coil coupled to an upper frame, and a rotor having a lower frame entirely formed of a metal to cover an outer circumference and a bottom of the stator, a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, and a support member formed as one unit with, and at a central portion of the lower frame coupled to a washing water shaft for transmission of a rotating force of the lower frame to the washing water shaft, thereby permitting smooth heat dissipation and drainage from the motor, and shortening a fabrication process and time period.
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1. Field of the Invention
The present invention relates to a washing machine, and more particularly, to a brushless motor for driving an inner tub or a pulsator in a washing machine.
2. Background of the Related Art
In general, the washing machine washes contaminated laundry clean by driving the inner tub or the pulsator by using a motor to circulate washing water having detergent contained therein.
That is, referring to
The operation of the aforementioned system will be explained.
Upon application of a power to the brushless motor 4, the rotor 20 of the motor rotates in one direction by a polarity difference from the stator 10 and a flow of magnetic flux along the back yoke 23, to rotate the support member 30 coupled to the lower frame 21 of the rotor 20. According to this, the shaft 5 coupled with the female serration 31 inside of the support member 30 receives the rotating force of the rotor 20 through the support member 30 to rotate the inner tub 1 coupled to the shaft 5, thereby facilitating washing of the laundry.
However, the related art brushless motor has the following various problems caused by the structure.
First, the general plastic injection molded lower frame 21 in the rotor 20 of the related art brushless motor 4 impedes smooth dissipation of a heat generated during operation of the motor 4 to keep accumulation of the heat inside of the motor 4, that causes thermal distortion of the lower frame 21 and various components, and degrades the performance rapidly and shortens a lifetime of the motor. Moreover, the many steps required for injection molding of the rotor 20 in fabrication of the brushless motor 4 takes much time period, which drops a productivity, and the reinforcement required for the rotor 20 increases a total weight.
Second, the requirement for a separate device, such as a jig(not shown), for fitting the magnets 22 to the related art lower frame 21 at fixed intervals leads to a complicated fabrication process. That is, the fastening of the magnets 22 to the jig and winding the back yoke 23 therearound for fitting the magnets 22 to the lower frame 21 requires many fabrication steps, that causes many defects, to increase a production cost.
SUMMARY OF THE INVENTIONAccordingly, the present invention is directed to a brushless motor in a washing machine that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a brushless motor in a washing machine, which can prevent an internal heating, for making a stable operation.
Another object of the present invention is to provide a brushless motor in a washing machine, which can simplify the steps of process for fitting the magnets to a rotor.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the brushless motor in a washing machine including a stator havihg a coil coupled to an upper frame, and a rotor having a lower frame entirely formed of a metal to cover an outer circumference and a bottom of the stator, a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, and a support member formed as one unit with, and at a central portion of the lower frame coupled to a washing water shaft for transmission of a rotating force of the lower frame to the washing water shaft.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention:
In the drawings:
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
Referring to
Though the lower frame 210 of the rotor 200 of steel plate in the first embodiment of the present invention permits, not only smooth heat dissipation of the heat from the motor 4, but also easy fitting of the magnets 220 on the lower frame 210, a property of the material causes a problem of short circuit. That is, once an insulation between the coil 120 of the stator 100 and the lower frame 210 of the rotor 200 are broken, a current flowed to the coil 120 flows to the lower frame 210, and, therefrom to the shaft 5 through the support member 300, and, eventually, to the inner tub 1 and the washing water in the outer tub 2, that may causes an accident. This is caused since the lower frame 210 and the support member 300 are formed of a conductive material as one unit. In a case the lower frame 210 and the support member 300 are formed of the same materials, a vibration caused by rotation of the rotor 200 is transmitted to the support frame 300 through the lower frame 210, and therefrom to the shaft 5. That is, since the materials are the same, the natural frequencies are the same, which allows direct transmission of the vibration occurred by the rotation of the lower frame 210 without attenuation, that results in complain from users as the vibration deteriorates a product reliability.
Accordingly, the second embodiment of the present invention suggests to provide a support member 300 formed of an insulating material different from a material of the lower frame 210. That is, the support member 300 of the insulating material can prevent flow of the current flowed along the lower frame 210 to the shaft 5 through the support member 300, even if the insulation between the coil 120 of the stator 100 and the lower frame 210 of the rotor 200 is broken. Furthermore, the formation of the lower frame 210 and the shaft 300 of different materials differ natural frequencies, to attenuate a portion of the vibration transmitted through the lower frame 210 by the shaft 300. It can be known that the attenuation of the vibration to the shaft 5 permits a low noise operation of the washing machine. On the other hand, the formation of the support member 300 of the insulating material causes to require additional reinforcement of the support member 300. Accordingly, as shown in
In the meantime, the formation of the lower frame 210 and the support member 300 of different materials may cause the fabrication process to form as one unit to require more steps. To cope with this, a third embodiment of the present invention suggests to form a support member 300 which can be coupled to the lower frame selectably, according to the following various methods. That is, as shown in
However, the present invention suggests a system as illustrated in
The brushless motor in a washing machine of the present invention has the following advantages as a material of the brushless motor is improved and various deficiencies resulted in following the change of material are supplemented.
Smooth hedt dissipation from the motor can be achieved, to prevent deterioration of a motor performance coming from the heat of the motor performance.
Smooth drainage of the washing water accumulated in the brushless motor can be achieved, to permit to prevent short circuit between the coil in the stator and the shaft in advance.
The easy and stable fitting of the magnets to the inside surface of the lower frame in the rotor shortens an overall fabrication process and time period.
It will be apparent to those skilled in the art that various modifications and variations can be made in the brushless motor in a washing machine of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Claims
1. A brushless motor in a washing machine, comprising:
- a stator having a coil, the stator coupled to an upper frame; and
- a rotor having a lower frame entirely formed of a metal to cover an outer circumference and a bottom of the stator, a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, and a support member formed as a single piece with the lower frame at a central portion thereof and coupled to a washing water shaft for transmission of rotating force of the lower frame to the washing water shaft, wherein the lower frame includes a plurality of grooves formed in a bottom surface thereof at fixed intervals along an inside circumference of the bottom surface, each having a drain hole in a bottom of the groove.
2. The brushless motor as claimed in claim 1, wherein the lower frame further includes a cooling fin between the grooves in the lower frame for dissipation of heat from the stator.
3. The brushless motor as claimed in claim 1, wherein the lower frame further includes projections on an inside circumference of the lower frame for fixing intervals of the magnets.
4. The brushless motor as claimed in claim 1, wherein a bottom surface of the support member and a surface of the lower frame have a plurality of fastening holes for fastening the support member and the lower frame with fastening means.
5. The brushless motor as claimed in claim 4, wherein the fastening means comprise bolts or rivets.
6. The brushless motor as claimed in claim 1, wherein the rotor having the lower surface entirely formed of a metal and configured such that the outer circumference of the rotor covers the plurality of magnets fitted to an inside wall thereof serves as the yoke.
7. A brushless motor in a washing machine, comprising:
- a stator having a coil, the stator coupled to an upper frame; and
- a rotor having a lower frame entirely formed of a metal to cover an outer circumference and a bottom of the stator, a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, and a support member formed as a single piece with the lower frame at a central portion thereof and coupled to a washing water shaft for transmission of rotating force of the lower frame to the washing water shaft, wherein the lower frame includes a plurality of grooves formed in a bottom surface thereof at fixed intervals along an inside circumference of the bottom surface, each having a drain hole in a bottom of the groove, wherein the lower frame her further includes a cooling fin between the grooves in the lower frame for dissipation of heat from the stator, and wherein the cooling fin is formed by lancing the lower frame, which forms a hole which is used as a draft hole.
8. A brushless motor in a washing machine, comprising:
- a stator having a coil, the stator coupled to an upper frame; and
- a rotor having a lower frame entirely formed of a metal to cover an outer circumference and a bottom of the stator, a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, and a support member formed of a single material and as a separate piece from the lower frame, and configured to be attached to the lower frame at a central portion thereof and directly coupled to a washing water shaft for transmission of rotating force of the lower frame to the washing water shaft, wherein the support member is formed of an insulating material that insulates it from the lower frame, and includes: a circular rib; radial ribs and reinforcing ribs extending from a circumference of the circular rib for reinforcing the lower frame; and a female serration for coupling the support member with the shaft, wherein the support member includes a plurality of downward coupling projections on a bottom surface thereof, and the lower frame includes a plurality of coupling holes opposite to the coupling projections for accepting the coupling projections on the support member, for coupling the support member and the lower frame.
9. A brushless motor in a washing machine, comprising:
- a stator having a coil, the stator coupled to an upper frame; and
- a rotor having a lower frame entirely formed of a metal to cover an outer circumference and a bottom of the stator, a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, and a support member formed at a central portion of the lower frame coupled to a washing water shaft for transmission of rotating force of the lower frame to the washing water shaft, wherein the lower frame further includes a cooling fin between grooves in the lower frame for dissipation of heat from the stator and wherein the cooling fin is formed by lancing the lower frame which forms a hole which is used as a draft hole.
10. A brushless motor in a washing machine, comprising:
- a stator having a coil, the stator coupled to an upper frame; and
- a rotor having a lower frame entirely formed of a metal to cover an outer circumference and a bottom of the stator, a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, and a support member formed at a central portion of the lower frame coupled to a washing water shaft for transmission of rotating force of the lower frame to the washing water shaft, wherein the support member is formed of an insulating material that insulates it from the lower frame, and includes: a circular rib; radial ribs and reinforcing ribs extending from a circumference of the circular rib for reinforcing the lower frame; and a female serration for coupling the support member with the shaft, wherein the support member includes a plurality of downward coupling projections on a bottom surface thereof, and the lower frame includes a plurality of coupling holes opposite to the coupling projections for accepting the coupling projections on the support member, for coupling the support member and the lower frame.
11. A brushless motor in a washing machine, comprising:
- a stator having a coil and coupled to an upper frame; and
- a rotor having a lower frame entirely formed of metal to cover an outer circumference and a bottom of the stator, and a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, wherein the lower frame further includes a cooling fin formed as a single piece with the rotor for dissipation of heat from the stator and wherein the cooling fin is formed by lancing and bending the lower frame which forms a hole which is used as a draft hole.
12. The brushless motor as claimed in claim 11, wherein the rotor has a support member formed at a central portion of the lower frame adjacent to the washing water shaft, wherein the lower frame further includes a plurality of grooves formed in a bottom surface of the lower frame at fixed intervals along an inside circumference of the bottom surface.
13. A brushless motor in a washing machine, comprising:
- a stator having a coil, and coupled to an upper frame; and
- a rotator having a lower frame entirely formed of a metal to cover an outer circumference and a bottom of the stator, and a plurality of magnets fitted to an inside wall of the lower frame at fixed intervals opposite to the coil of the stator, and a plurality of grooves formed in a bottom surface of the lower frame at fixed intervals along an inside circumference of the bottom surface, wherein the grooves are formed in a radial direction of the lower frame, wherein the grooves are formed by pressing the lower frame, and a drain hole provided in a bottom of at least one of the grooves.
14. A motor for a washing machine, comprising:
- a drive shaft;
- a stator;
- a rotor comprising a frame formed entirely of steel and configured to cover at least a portion of the stator, the rotor having a plurality of magnets positioned adjacent to a sidewall of the rotor and a bottom surface adjacent the sidewall, wherein a center portion of the rotor protrudes toward the stator and comprises a plurality of coupling holes and at least one fastening hole; and
- a support member configured to connect the rotor to the drive shaft, wherein the support member comprises a plurality of fastening holes and at least one coupling projection configured to be inserted into a corresponding coupling hole of the rotor.
15. A motor for a washing machine, comprising:
- a drive shaft;
- a stator;
- a rotor comprising a frame formed entirely of steel and configured to cover at least a portion of the stator, the rotor having a plurality of magnets positioned adjacent to a sidewall of the rotor and a bottom surface adjacent the sidewall, wherein a center portion of the rotor protrudes toward the stator and includes a central opening having a projecting lip; and
- a support member configured to connect the rotor to the drive shaft and having an opening for receiving therein the drive shaft, wherein corresponding projections and recesses are formed on mating portions of the drive shaft and the opening of the support member, and wherein the projecting lip of the rotor is configured to bear against and support the support member.
16. The motor of claim 15, wherein the support member comprises at least one reinforcing rib.
17. The motor of claim 16, wherein the at least one reinforcing rib comprises at least one circular rib.
18. The motor of claim 15, wherein the projecting lip extends substantially perpendicular to the bottom surface of the rotor, and then curves inward.
19. A washing machine, comprising:
- an outer tub;
- an inner tub rotatably mounted within the outer tub; and
- a motor comprising: drive shaft connected to the inner tub; a single stator comprising a coil; and a rotor comprising a frame formed entirely of steel and configured to cover at least a portion of the stator and to be connected to the drive shaft, the rotor having a plurality of magnets positioned adjacent to a sidewall of the rotor, a bottom surface adjacent the sidewall, and a plurality of cooling fins configured to project from the bottom surface of the rotor, wherein the sidewall comprises an extending lip at an end of the sidewall opposite the bottom surface of the rotor, and wherein the lip comprises a first portion that extends substantially perpendicular to the sidewall of the rotor, and a second portion that extends substantially perpendicular to the first portion.
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Type: Grant
Filed: May 26, 2004
Date of Patent: Aug 2, 2011
Assignee: LG Electronics Inc. (Seoul)
Inventors: In Geun Ahn (Kyongsangnam-do), Dong Beom Lee (Changwon-shi), Jong Chul Bang (Changwon-shi)
Primary Examiner: Burton Mullins
Attorney: KED & Associates, LLP
Application Number: 10/853,764
International Classification: H02K 1/28 (20060101); D06F 37/40 (20060101);