Washing machine

Abstract

A washing machine, more particularly, an improvement in the structure of a drive unit included in a drum type washing machine is disclosed. The washing machine includes a tub for receiving wash water therein, a drum rotatably disposed in the tub and adapted to wash laundry received therein, a shaft penetrated through the tub to thereby be connected to the drum, the shaft being adapted to transmit a drive force of a motor to the drum, a stator coupled fixedly to a rear wall portion of the tub, and a rotor including at least one magnet, a back yoke defining a magnetic path, and a rotor frame rotatably disposed at the outside of the stator, the rotor frame being connected to the shaft so as to transmit a rotating force of the rotor to the shaft. The rotor frame includes a side wall portion and a rear wall portion, and is made of an aluminum material.

Description

[0001] This application claims the benefit of the Korean Patent Application Nos. 10-2005-0111504, 10-2005-0111505, 10-2005-0111506 and 10-2005-0111507 filed on Nov. 21, 2005 which are hereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a washing machine, and more particularly, to an improvement in the structure of a drive unit included in a drum type washing machine.

[0004] 2. Discussion of the Related Art

[0005] Generally, drum type washing machines are designed to perform a washing operation by use of a frictional force between a drum and laundry as the drum is rotated by a drive force of a motor transmitted thereto in a state wherein the laundry is received in the drum together with wash water and detergent. The above described washing operation manner has several effects of causing damage to laundry as little as possible while preventing entangling of laundry and also providing excellent washing effects by pounding and rubbing.

[0006] Now, the configuration of a conventional drum type washing machine will be described in brief with reference to FIG. 1.

[0007] Referring to FIG. 1 illustrating the configuration of the conventional drum type washing machine in longitudinal sectional view, the conventional washing machine comprises a tub 2 installed in a cabinet 1 and a drum 3 rotatably installed in the center of the tub 2.

[0008] The tub 2 is mounted, at a lower side thereof, with a motor 5a and in turn, the motor 5a is connected to a motor pulley 18 by means of a shaft.

[0009] The drum 3 is mounted, at a rear side thereof, with a drum shaft, and a drum pulley 19 is mounted on the drum shaft.

[0010] The drum pulley 19 mounted on the drum shaft and the motor pulley 18 connected to the motor 5a are connected to each other by means of a belt 20 as a power transmission element.

[0011] The cabinet 1 is provided, at a front side thereof, with a door 21, and a gasket 22 is provided between the door 21 and the tub 2.

[0012] A hanging spring 23 is mounted between an inner ceiling surface of the cabinet 1 and an outer upper surface of the tub 2 and adapted to support the tub 2. Also, a friction damper 24 is mounted between an inner bottom surface of the cabinet 1 and an outer lower surface of the tub 2 and adapted to alleviate vibration of the tub 2 caused during a dehydrating operation.

[0013] In the above described conventional washing machine, a drive force of the motor 5a is transmitted to the drum 3 by way of the motor pulley 18, the drum pulley 19, and the belt 20 connecting the motor pulley 18 and the drum pulley 19 to each other. Such an indirect power transmission manner, however, has the following problems.

[0014] Firstly, since the drive force of the motor 5a is transmitted to the drum 3 through the belt 20 wound on both the motor pulley 18 and the drum pulley 19 rather than being directly transmitted to the drum 3, there is a high potential loss of energy in the transmission course of the drive force.

[0015] Secondly, in the course of transmitting the drive force of the motor 5a to the drum 3 through the above described several elements, such as the motor pulley 18, the drum pulley 19, and the belt 20, and the like, there inevitably exists a problem of severe noise as compared to the case where the drive force is directly transmitted to the drum 3.

[0016] Thirdly, a necessity for a great number of elements for transmitting the drive force of the motor 5a to the drum 3, such as the motor pulley 18, the drum pulley 19, the belt 20, and the like, consequently, causes a complicated product assembling operation.

[0017] Fourthly, the above described great number of elements for transmitting the drive force of the motor 5a to the drum 3 may result in a proportional increase in the number of potential failure areas, and this has a problem of increasing the generation frequency of failures.

[0018] In conclusion, due to the above described power transmission manner in which the drive force of the motor 5a is indirectly transmitted to the drum 3 only by way of the motor pulley 18, the belt 20, and the drum pulley 19, the conventional drum type washing machine has problems of a high potentiality of failures and noise generation as well as excessive consumption of energy and seriously, may result in deterioration in washing performance thereof, etc.

[0019] To solve the above described problems, the applicant of the present invention has proposed to use a direct connection type motor in a drive unit of a drum type washing machine, as disclosed in Korean Patent Laid-open Publication No. 10-2001-0037607.

[0020] In the above published patent invention, there is provided a rotor frame, which is formed by pressing an iron plate and installed to transmit a rotating force of a rotor to a drum directly while performing itself the function of a back yoke having a magnetic path. It could be found that the disclosed rotor frame has a capability of solving the above described problems of the indirect power transmission manner while achieving a simplified structure.

[0021] However, forming the rotor frame by pressing the iron plate has a difficulty, due to characteristics of a press operation, to obtain a required accuracy, more particularly, concentricity, when the thickness of the iron plate exceeds a predetermined value. On the other hand, when the rotor frame is formed by use of an iron plate having a thickness less than the predetermined value, there is a problem in that the rotor frame cannot obtain a required strength and may fluctuate during rotation.

[0022] Furthermore, to provide a passage of magnetic flux, that is to say, a magnetic path for the flow of magnetic flux generated by electric current flowing through coils of a stator, it is essential to provide a back yoke, which is made of a magnetic material and has an appropriate thickness, behind a magnet. Here, it is noted that the thinner the thickness of the back yoke, the lower a saturation point of the magnetic flux. Accordingly, when the rotor frame serving as the back yoke has a small thickness, there is a limit to increase the output of a motor even if the amount of current is increased to obtain a strong output.

[0023] Consequently, the attempt to form the rotor frame having the function of the back yoke by use of the iron plate in views of diversification of products reaches a limit due to the above described thickness problem of the rotor frame.

[0024] Also, due to characteristics of the iron plate, there is a risk in that the rotor frame tends to gather rust on its surface easily. The rust may cause deterioration in the strength of the rotor frame and in the worst case, there is a risk in that rust powder that falls from the rotor frame is attached in an air gap between the magnet and the stator, thereby acting to restrict rotation of the rotor.

[0025] In addition, the rotor frame, made of the iron plate, has a difficulty in the implementation of any subsequent process for improving accuracy and other processes.

SUMMARY OF THE INVENTION

[0026] Accordingly, the present invention is directed to a washing machine that substantially obviates one or more problems due to limitations and disadvantages of the related art.

[0027] An object of the present invention is to provide a drum type washing machine in which a drive unit, more particularly, a rotor frame that is adapted to transmit a rotating force of a rotor to a shaft directly, has an improved structure suitable to transmit a drive force of a motor to a drum directly, thereby achieving the effects of reducing the generation potential of noise and failure as well as excessive consumption of energy and of increasing the durability and stability of the washing machine.

[0028] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0029] To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a washing machine comprising: a tub for receiving wash water therein; a drum rotatably disposed in the tub and adapted to wash laundry received therein; a shaft penetrated through the tub to thereby be connected to the drum, the shaft being adapted to transmit a drive force of a motor to the drum; a stator coupled fixedly to a rear wall portion of the tub; and a rotor including at least one magnet, a back yoke defining a magnetic path, and a rotor frame rotatably disposed at the outside of the stator, the rotor frame being connected to the shaft so as to transmit a rotating force of the rotor to the shaft, wherein the rotor frame comprises a side wall portion and a rear wall portion, and is made of an aluminum material.

[0030] The coupling structure between the tub and the stator may be altered in various manners and thus, the detailed configuration and method for accomplishing the above coupling structure also may be altered in various manners.

[0031] Preferably, the rotor frame is formed by die casting, and the side wall portion and the rear wall portion of the rotor frame are integrally formed with each other.

[0032] The rear wall portion of the rotor frame may be provided, at a center position thereof, with a connector, which is serration-coupled onto an outer circumference of the shaft and adapted to transmit the rotating force of the rotor to the shaft. Here, the connector may be made of an insulating material and integrally formed with the rotor frame by insert molding.

[0033] The washing machine may further comprise: a bearing housing provided between the rear wall portion of the tub and the stator and coupled fixedly to both the tub and the stator, the bearing housing receiving at least one bearing therein to rotatably support the shaft. Preferably, the bearing housing is made of a metallic material.

[0034] Preferably, the side wall portion of the rotor frame is extended forward from an edge of the rear wall portion, and the side wall portion of the rotor frame is formed, in a circumferential direction thereof, with a ledge having a seating plane for supporting the magnet thereon. With this configuration, the magnet can be more stably secured to the rotor frame.

[0035] Preferably, the stator comprises: a stator core including at least one winding portion around which a coil is wound and an annular body portion defining the magnetic path; and an insulator for insulating the stator core from the coil. The stator may have thirty six poles, and the rotor may have forty eight poles.

[0036] The back yoke may be attached to an inner surface of the side wall portion of the rotor frame in a circumferential direction by use of an adhesive, and the magnet may be attached to an inner surface of the back yoke in a circumferential direction by use of an adhesive. The back yoke is made of a magnetic material to define the magnetic path. Here, the back yoke may be fabricated to have an optical thickness in views of the performance of the motor.

[0037] The above described drum type washing machine according to the present invention has the following effects.

[0038] Firstly, the washing machine of the present invention has a direct connection motor and thus, has the effect of significantly reducing the generation of noise and failure as well as the loss of power. Also, with the use of the metallic bearing housing, the washing machine of the present invention is applicable to products having a high-temperature drying function, without the risk of thermal deformation.

[0039] Secondly, in the washing machine of the present invention, the rotor frame is made of an aluminum material and thus, has no risk of gathering rust thereon. This results in an increase in the durability of the motor.

[0040] Thirdly, the rotor frame of the present invention has a magnet seating plane for achieving a highly efficient mounting operation of the magnet. Also, with the provision of vent holes having the function of moisture discharge and ventilation, it is possible to prevent overheating of the motor while protecting the motor from invasion of moisture. This consequently has the effect of increasing the reliability of the motor and extending the lifespan of the motor.

[0041] Fourthly, according to the present invention, the rotor frame is formed by die casting an aluminum material. Accordingly, the rotor frame can be manufactured with a simplified manner while guaranteeing an improved processability required for any subsequent process. Also, forming the rotor frame by use of a light-weight material is efficient to minimize the power loss of the motor due to the inertia force of the rotor frame.

[0042] Fifthly, the aluminum rotor frame provides a flexibility to ensure freely change in the thickness of the back yoke in views of diversification of products. This enables an increase in the overall thickness of the rotor frame and consequently, the rotor frame is free from unwanted fluctuation during rotation thereof, thus resulting in reduced noise and vibration. In addition, the change possibility of the thickness is advantageously applicable for the sake of reinforcing the strength of the rotor frame.

[0043] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:

[0045] FIG. 1 is a longitudinal sectional view illustrating the configuration of a drive unit included in a conventional drum type washing machine;

[0046] FIG. 2 is a longitudinal sectional view illustrating important parts of a drum type washing machine according to a first embodiment of the present invention;

[0047] FIG. 3 is a right side view of FIG. 2, in which the illustration of a motor is omitted;

[0048] FIG. 4 is a partially cut-away perspective view illustrating a rotor shown in FIG. 2;

[0049] FIG. 5 is a perspective view illustrating a stator shown in FIG. 2;

[0050] FIG. 6 is a perspective view illustrating a connector shown in FIG. 2;

[0051] FIG. 7 is a bottom perspective view of FIG. 6;

[0052] FIG. 8 is a longitudinal sectional view schematically illustrating the configuration of a drum type washing machine using a direct connection motor according to a second embodiment of the present invention;

[0053] FIG. 9 is an enlarged longitudinal section view of the portion "A" of FIG. 8, illustrating the configuration of a drive unit included in the drum type washing machine according to the second embodiment of the present invention;

[0054] FIG. 10 is a partially cut-away perspective view illustrating the configuration of a rear wall portion of a tub shown in FIG. 9;

[0055] FIG. 11 is a perspective view illustrating a bearing housing shown in FIG. 9;

[0056] FIG. 12 is a bottom perspective view of FIG. 11;

[0057] FIG. 13 is a sectional view taken along the line I-I of FIG. 11;

[0058] FIG. 14 is a longitudinal sectional view illustrating the configuration of a drum type washing machine using a direct connection motor according to a third embodiment of the present invention; and

[0059] FIG. 15 is a longitudinal sectional view illustrating the configuration of a drum type washing machine using a direct connection motor according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0060] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0061] In the present invention, a motor, more particularly, a stator is coupled fixedly to a rear wall portion of a tub. A method for coupling the stator to the tub may be changed according to respective preferred embodiments of the present invention.

[0062] Now, a first embodiment of the present invention will be described in detail with reference to FIGS. 2 to 7.

[0063] FIG. 2 is a longitudinal sectional view illustrating important parts of a drum type washing machine according to a first embodiment of the present invention, and FIG. 3 is a right side view of FIG. 2, in which the illustration of a motor is omitted.

[0064] FIG. 4 is a partially cut-away perspective view illustrating a rotor shown in FIG. 2, FIG. 5 is a perspective view illustrating a stator shown in FIG. 2, FIG. 6 is a perspective view illustrating a connector shown in FIG. 2, and FIG. 7 is a bottom perspective view of FIG. 6.

[0065] The drum type washing machine according to the present embodiment comprises a tub 2 installed in a cabinet (not shown) and used to receive wash water therein, a drum 3 rotatably provided in the tub 2 and adapted to wash laundry received therein as it is rotated, a shaft 4 penetrated through the tub 2 and connected to the drum 3, the shaft 4 being adapted to transmit a drive force of a motor 5 to the drum 3, and a stator 14 having winding portions around which coils are wound, the stator 14 being coupled fixedly to a rear wall portion of the tub 2.

[0066] In the present embodiment, the washing machine further comprises a rotor 13, which includes magnets 13c, a back yoke 300 having a magnetic path, and a rotor frame rotatably disposed around the stator 14. Here, the rotor frame is connected to the shaft 4, to transmit a rotating force of the rotor 13 to the shaft 4.

[0067] The rotor frame has a side wall portion 13b and a rear wall portion 13a, and is made of an aluminum material.

[0068] In the present embodiment, the washing machine may further comprise a front bearing 6a and a rear bearing 6b installed, respectively, on an outer circumference of either end of the shaft 4, and a bearing housing 7 provided on a rear wall surface 200 of the tub 2 for supporting the front and rear bearings 6a and 6b.

[0069] In the present embodiment, a connector 16 may be provided in such a manner that it is serration-coupled onto an outer circumference of the shaft 4, in particular, at a position behind the rear bearing 6b and also, coupled to the rotor 13, thereby serving to transmit the rotating force of the rotor 13 to the shaft 4.

[0070] Here, the bearing housing 7 is provided between the rear wall surface 200 of the tub 2 and the stator 4 so that it is coupled fixedly to both the tub 2 and the stator 4. Also, the bearing housing 7 is adapted to rotatably support the shaft 4 by means of the front bearing 6a and the rear bearing 6b.

[0071] In this case, the bearing housing 7 is made of a metallic material, preferably, made of an aluminum alloy. Also, preferably, the connector 16 is made of an insulating material and integrally formed with the rotor frame via insert molding.

[0072] The metallic bearing housing 7 is integrally formed, at a center portion thereof, with a hub 700. The front and rear bearings 6a and 6b are located in the hub 700. Around the hub 700 are formed a plurality of coupling bosses 701 in such a manner that the coupling bosses 701 are spaced apart from another by a regular distance in a circumferential direction of the hub 700. The coupling bosses 701 are used to secure the stator 14 to the bearing housing 7 by use of coupling members 15d. The above described configuration of the bearing housing 7 is clearly shown in FIG. 3.

[0073] The hub 700, which is located at the center portion of the metallic bearing housing 7, is formed, at different positions of an inner circumference thereof, with short-stepped portions 8a and 8b. The short-stepped portions 8a and 8b serve to support the front and rear bearings 6a and 6b, respectively, so as to prevent the respective bearings 6a and 6b from being separated from the bearing housing 7.

[0074] Of the short-stepped portions 8a and 8b formed along the inner circumference of the bearing housing 7, the short-stepped portion 8a, which is formed at a front position, has an "L"-shaped form suitable to support a rear end of the front bearing 6a that is installed on the outer circumference of a front end of the shaft 4. On the other hand, the short-stepped portion 8b, which is formed at a rear position, has an "L"-shaped form suitable to support a front end of the rear bearing 6b that is installed on the outer circumference of a rear end of the shaft 4.

[0075] The shaft 4, which is located in the bearing housing 7 and adapted to transmit the drive force of the motor 5 to the drum 3, is formed, at front and rear locations on the outer circumference thereof, with positioning short-stepped portions 9a and 9b for determining the installation positions of the front and rear bearings 6a and 6b on the shaft 4.

[0076] The front end of the shaft 4 is coupled to a spider 10 that is provided at a rear wall portion of the drum 3. Also, to prevent the shaft 4 from gathering rust thereon, a brass bushing 11 is press fitted around a portion of the shaft 4 extended between the spider 10 and the front bearing 6a. Here, the bushing 11 is provided, around an outer circumference thereof, with a sealing member 12 for preventing permeation of moisture into the bearings 6a and 6b.

[0077] The rotor 13, which constitutes a part of a direct connection motor 5, is coaxially coupled to the rear end of the shaft 4. The stator 14 is located inside the rotor 13 so as to constitute the direct connection motor 5 along with the rotor 13. Here, the stator 14 is coupled fixedly to the coupling bosses 701 of the bearing housing 7. Of course, it will be appreciated that the coupling bosses 701 may be formed at the stator 14.

[0078] The rotor 13 includes the aluminum rotor frame.

[0079] As shown in FIG. 4, preferably, the rotor frame has the side wall portion 13b and the rear wall portion 13a, which are integrally formed with each other, and is formed by die casting an aluminum material.

[0080] Specifically, the side wall portion 13b of the rotor frame is extended forward from an edge of the rear wall portion 13a in a direction perpendicular to the rear wall portion 13a. The side wall portion 13b is formed, in a circumferential direction thereof, with a ledge having a seating plane 130 for supporting the magnets 13c that are attached to an inner surface of the side wall portion 13b in a front portion of the inner surface. The rear wall portion 13a of the rotor frame is centrally formed with a hub 132. Here, the hub 132 is coupled to the connector 16, to allow the rotating force of the rotor 13 to be transmitted to the shaft 4 through the connector 16.

[0081] Around the hub 132 of the rotor frame are radially formed a plurality of cooling fins 133. The cooling fins 133 serve to blow air toward the stator 14 during rotation of the rotor 13, so as to remove heat generated in the stator 14. In this case, each of the cooling fins 133 is formed to have a predetermined length in a radial direction of the rotor frame.

[0082] Preferably, the cooling fins 133 are integrally formed with the rotor frame and extend radially from the hub 132 to the ledge to have a height difference between the hub 132 and the ledge. On the basis of the height difference, the cooling fins 133 can be linearly formed or curved convexly or concavely. With this configuration, the cooling fins 133 can act to blow air concentratively to specific portions of the stator 14 having the highest cooling requirement.

[0083] Although FIG. 4 illustrates the cooling fins 133 that are configured to have the highest height at the side of the hub 132, it will be appreciated that, conversely, the cooling fins 133 have the highest height at the side of the ledge.

[0084] In the present invention, the rear wall portion 13a of the rotor frame has a plurality of vent holes 134 perforated between the respective adjacent cooling fins 133. The vent holes 134 have the roles of moisture discharge and ventilation.

[0085] With the provision of the cooling fins 133 and the hub 132, the rotor frame of the present invention can achieve a reinforced rigidity of the rear wall portion 13b. Also, the cooling fins 133 and the hub 132 can be formed simultaneously via a single fabrication process and therefore, achieve a reduction in manufacturing costs.

[0086] The hub 132 of the rotor 13 has a center through-hole 131, a plurality of coupling holes 137 equidistantly formed around the center through-hole 131, and a plurality of positioning holes 138 equidistantly formed around the center through-hole 131 between the respective adjacent coupling holes 137. The coupling holes 137 are used to couple the connector 16 to the rotor 13. Here, the connector 16 is serration-coupled onto the outer circumference of the rear end of the shaft 4 at a position behind the rear bearing 6b. The positioning holes 138 are used to determine the assembling position of the connector 16. Here, a coupling member 15a is coupled into the shaft 4 by passing through the through-hole 131. With the use of the coupling member 15a, there is no risk in that the shaft 4 is unintentionally separated from the connector 16.

[0087] The connector 16 is made of a resin material having a different vibration mode from that of the aluminum rotor 13. Preferably, the connector 16 is made of an insulating material and integrally formed with the rotor frame via insert molding.

[0088] The connector 16, as shown in FIGS. 2, 6, and 7, has coupling holes 162 perforated in an edge region thereof along a circumferential direction, to correspond to the coupling holes 137 formed in the hub 132 of the rotor 13. The connector 16 also has positioning protrusions 160 integrally formed at positions between the respective adjacent coupling holes 162. As the positioning protrusions 160 are inserted into the positioning holes 138 of the rotor 13, the coupling holes 137 of the rotor 13 are automatically aligned with the coupling holes 162 of the connector 16.

[0089] In addition, the connector 16 has a center hub 163, a serration 164 formed at an inner circumference of the hub 163 to be engaged with a serration 400 formed on the rear end of the shaft 4, and reinforcing ribs 161 formed at an outer circumference of the hub 163 for reinforcing the strength of the hub 163.

[0090] As shown in FIGS. 2 and 5, the stator 14, which constitutes the motor 5 along with the rotor 13, includes a ring-shaped insulator 140, and coils 142 wound on winding portions 141 arranged at the outside of the insulator 140. In addition, coupling ribs 143 are integrally formed with the insulator 140 inside the insulator 140, to secure the stator 14 to the bearing housing 7.

[0091] The stator further includes a stator core, which consists of the winding portions 141 around which the coils 142 are wound, and an annular body portion having a magnetic path. The insulator 140 serves to insulate the stator core and the coils 142 from each other.

[0092] The stator core may be an annular spiral core having a multilayered structure, which is obtained by spirally winding an iron plate, consisting of the winding portions 141 and the body portion, from the lowermost layer to the uppermost layer.

[0093] Alternatively, the stator core may take the form of an annular sectional core, which is obtained by coupling a plurality of arched stator core sections, each consisting of a plurality of arched stator core pieces stacked one above another in multiple layers, with one another.

[0094] A tub bracket 17 is coupled onto an outer circumference of the tub 2 and adapted to secure the bearing housing 7 at the rear side of the tub 2. In this case, a method for coupling the tub bracket 17 to the tub 2 may be changed according to the material of the tub 2. For example, if the tub 2 is made of stainless steel, preferably, tub bracket 17 may be coupled to the tub 2 by welding.

[0095] Here, the tub bracket 17 has extensions, which are extended rearward beyond the rear wall surface 200 of the tub 2. Each extension of the tub bracket 17 is perforated with a coupling hole 170 so that an associated one of the coupling members 15d is penetrated through the coupling hole 170, to thereby be coupled into an associated coupling recess 702 of the bearing housing 7.

[0096] The bearing housing 7 has a plurality of extensions radially extended from the center thereof. As the extensions are coupled to the tub bracket 17, the bearing housing 7 is secured to the tub 2. If the bearing housing 7 has three extensions, it can be called "trivet type".

[0097] The bearing housing 7 has a self-aligning rib 703 formed in a circumferential direction thereof at the outside of the coupling bosses 701, the self-aligning rib 703 having a ramp 703a at a side thereof. To correspond to the self-aligning rib 703, the insulator 140 of the stator 14, which is coupled to the coupling bosses 701 of the bearing housing 7, has a self-aligning rib 144 formed at an inner circumference thereof in a circumferential direction. Similarly, the self-aligning rib 144 has a ramp 144a at a side thereof, so as to be engaged with the ramp 703a of the self-aligning rib 703 of the bearing housing 7.

[0098] Now, the operation of the drive unit having the above described configuration, which is included in the drum type washing machine according to the first embodiment of the present invention, will be described.

[0099] If the rotor 13 is rotated as electric current is sequentially applied to the respective coils 142 of the stator 14 under the control of a motor driving controller (not shown) attached to a control panel, the shaft 4, which is serration-coupled to the connector 16 coupled to the rotor 13, is rotated. Thereby, power is transmitted to the drum 3 through the shaft 4, thus enabling rotation of the drum 3.

[0100] Meanwhile, in the present embodiment, preferably, the stator 14 has thirty six poles and the rotor has forty eight poles. The greater the number of the poles, the easier the positional detection and control of the stator and the rotor can be accomplished.

[0101] Here, the forty eight poles of the rotor alternately define a north pole and a south pole in such a manner that twelve permanent magnets, each having a total of four poles, are coupled inside the rotor frame. The permanent magnets may be coupled by use of an adhesive.

[0102] Of course, the back yoke also may be coupled inside the rotor frame by use of an adhesive. Here, the back yoke has to be made of a magnetic material because it must have a magnetic path.

[0103] Hereinafter, the assembling procedure and effects of the drive unit included in the drum type washing machine according to the first embodiment of the present invention will be described.

[0104] First, the bearing housing 7 of the present invention is coupled to the tub bracket 17 by use of the coupling members 15d as the coupling members 15d are penetrated through the coupling holes 170 of the tub bracket 17. Here, the tub bracket 17 was previously welded to the outer circumference of the tub 2. Thereby, the bearing housing 7 is secured to the rear side of the tub 2.

[0105] That is to say, in a state wherein the tub bracket 17 is welded fixedly to the outer circumference of the tub 2, the bearing housing 7 is coupled to the tub bracket 17 to thereby be mounted onto the rear side of the tub 2.

[0106] The assembled bearing housing 7 is made of a metallic material, such as an aluminum alloy and the like, and therefore, has no thermal deformation even under a high temperature condition. Accordingly, the bearing housing 7 is applicable to a drum type washing machine having a high-temperature drying cycle.

[0107] In the present invention, the bearing housing 7 is formed, at the front and rear positions of the inner circumference thereof, with the "L"-shaped short-stepped portions 8a and 8b. Accordingly, once the front and rear bearings 6a and 6b are mounted on the outer circumference of both the ends of the shaft 4, the rear end of the front bearing 6a and the front end of the rear bearing 6b can be supported by the short-stepped portions 8a and 8b, respectively.

[0108] That is to say, the metallic bearing housing 7 is able to support both the bearings 6a and 6b without the risk of unintentional separation by use of the short-stepped portions 8a and 8b formed at opposite positions of the inner circumference thereof.

[0109] Also, the shaft 4, which is located inside the bearing housing 7 and adapted to transmit the drive force of the motor 5 to the drum 3, is formed, at the front and rear locations on the outer circumference thereof, with the positioning short-stepped portions 9a and 9b, whereby the assembling positions of the front bearing 6a and the rear bearing 6b on the shaft 4 can be easily determined.

[0110] As described above, the front end of the shaft 4 is coupled to the spider 10 that is provided at the rear wall portion of the drum 3, and the brass bushing 11 is forcibly press fitted around the portion of the shaft 4 between the spider 10 and the front bearing 6a to prevent the shaft 4 from gathering rust thereon.

[0111] Also, the sealing member 12 is installed around the outer circumference of the bushing 11 to prevent invasion of moisture into the bearings 6a and 6b.

[0112] Meanwhile, the bearing housing 7 has the coupling bosses 701 equidistantly formed in a circumference thereof at the outside of the hub 700. Thereby, as the coupling members 15d, having penetrated through the stator 14, are coupled to the coupling bosses 701, the stator 14 can be strongly secured to the bearing housing 7.

[0113] Here, since the rotor frame is formed by die casting an aluminum material, it can be fabricated with a simplified process without the risk of rust. In addition, the rotor frame has a light weight due to characteristics of the aluminum material, and this is efficient to reduce the inertia loss of the rotor frame while achieving an improvement in processability. In conclusion, by integrally forming the rotor frame with the rotor by use of the aluminum material, more particularly, an aluminum alloy, etc., the manufacture of the rotor can be simplified considerably. Also, when it is desired to perform an additional process on the rotor frame for the sake of a more accurate structure, the processing of the rotor can be accomplished easily by virtue of its improved processability.

[0114] Meanwhile, by the coupling holes 137 for the coupling of the connector 16 and the positioning holes 138 for the determination of the assembling position of the connector 16, which are formed around the through-hole 131 in the hub 132 of the rotor frame, the connector 16, which will be serration-coupled to the outer circumference of the rear end of the shaft 4 at a position behind the rear bearing 6b, can be easily assembled to the rotor 13.

[0115] Specifically, once the positioning protrusions 160 of the connector 16 are inserted into and engaged in the positioning holes 138 of the rotor 13, the coupling holes 137 of the rotor 13 are automatically aligned with the coupling holes 162 of the connector 16, thus allowing the coupling members 15b to be coupled through the coupling holes 137 and 162 of the rotor 13 and the connector 16. As a result, the connector 16 can be easily assembled with the rotor 13.

[0116] In this case, the connector 16 is injection molded by use of a resin material and has a different vibration mode from the aluminum rotor 13. Accordingly, the connector 16 serves to allow the vibration of the rotor 13 to be transmitted to the shaft 4 in an alleviated state. Here, it is noted that the connector 16 may be integrally formed with the rotor frame via insert molding.

[0117] The connector 16 is formed with the serration 164 at the inner circumference of the hub 163. Accordingly, as the serration 164 are engaged with the serration 400 formed at the rear end of the shaft 4, the rotating force of the rotor 13 can be directly transmitted to the shaft 4 through the connector 16.

[0118] The connector 16 is also formed at the outer circumference of the hub 163 with the reinforcing ribs 601 to reinforce the strength of the hub 163.

[0119] Hereinafter, a drum type washing machine according to a second embodiment of the present invention will be described in detail with reference to FIGS. 8 to 13. The present embodiment has approximately the same configuration as that of the above described first embodiment except for a structure for coupling fixedly the motor to the rear wall portion of the tub. Accordingly, the description of the same configuration as the above described embodiment will be omitted.

[0120] FIG. 8 is a longitudinal sectional view schematically illustrating the configuration of a drum type washing machine using a direct connection motor according to the present embodiment, and FIG. 9 is an enlarged longitudinal sectional view of the portion "A" of FIG. 8, illustrating the configuration of a drive unit included in the drum type washing machine according to the second embodiment of the present invention.

[0121] FIG. 10 is a perspective view illustrating the rear wall portion of the tub shown in FIG. 9, FIG. 11 is a top perspective view of the bearing housing shown in FIG. 9, FIG. 12 is a rear perspective view of the bearing housing, and FIG. 13 is a sectional view taken along the line I-I of FIG. 11.

[0122] The present embodiment has a feature in that a bearing housing 7' is integrally formed with the tub 2, which is made of a plastic material, at the center of the rear wall portion of the tub 2. The bearing housing 7' of the present embodiment can rotatably support the shaft 4 while allowing a stator 6 to be coupled fixedly to the rear wall portion of the tub 2 therethrough.

[0123] Here, the bearing housing 7' is made of an aluminum alloy, etc. In the present embodiment, the bearing housing 7' is inserted into the rear wall portion of the tub 2 while the plastic tub 2 is injection molded, so as to be integrally formed with the rear wall portion of the tub 2.

[0124] Referring to FIG. 9, the bearing housing 7' includes a bearing supporting portion 7a for supporting bearings, the bearing supporting portion 7a having a sleeve form, and a stator coupling portion 7b integrally formed with the bearing supporting portion 7a to be extended radially from a rear end of the bearing supporting portion 7a. The stator coupling portion 7b is inserted into the rear wall portion of the tub 2 so that only stator coupling holes 700b formed in the stator coupling portion 7b are exposed to the outside.

[0125] Referring to FIGS. 11 and 12, the stator coupling portion 7b of the bearing housing 7' is extended radially and outwardly from the bearing supporting portion 7a in the form of a sleeve, and has stepped regions 70b-1, each of the stepped portions 70b-1 being stepped at least one time in a radial outward direction thereof.

[0126] The stator coupling portion 7b of the bearing housing 7' further has plane regions 70b-2 defined between the respective adjacent stepped regions 70b-1.

[0127] The bearing housing 7' of the present embodiment has a feature in that the stepped regions 70b-1 and the plane regions 70b-2 of the stator coupling portion 7b are continuously arranged to be connected to each other.

[0128] That is to say, the stator coupling portion 7b of the bearing housing 7' consists of the stepped regions 70b-1 configured to be stepped in a radial outward direction thereof and the plane regions 70b-2 configured to define planes between the respective adjacent stepped regions 70b-1. Here, of the regions of the stator coupling portion 7b, the regions 70b-1 are extended in a radial outward direction from the upper end of the bearing supporting portion 7a so that they are stepped downward per a predetermined distance in the radial outward direction. Also, of the regions of the stator coupling portion 7b, the regions 70b-2 are connected to a front end of the bearing housing 7' and have a plane structure.

[0129] The bearing housing 7' is formed, around a rear end thereof, with a resin filling groove 750a, for the sake of improving a coupling force with the tub 2 during insert injection molding.

[0130] Referring to FIGS. 10 and 11, the stator coupling portion 7b has positioning recesses 710b formed near some of the stator coupling holes 700b at positions corresponding to positioning protrusions formed at the stator 6.

[0131] As shown in FIG. 10, the rear wall portion of the tub 2 is formed with a plurality of protruding bosses 210 at positions corresponding to specific positions near the stator coupling holes 700b of the stator coupling portion 7b included in the bearing housing 7'. The protruding bosses 210 serve to prevent the stator 6 from coming into direct contact with the stator coupling portion 7b, in order to prevent an insulator of the stator 6 from being damaged by a coupling force applied in the course of coupling the stator 6.

[0132] Preferably, the stator coupling portion 7b is formed with a rib 720b in a circumferential direction at a position spaced apart from the center of the bearing supporting portion 7a by a predetermined distance, for the sake of increasing a coupling force with a resin material upon injection molding of the tub 2. Although it is preferable that coupling bosses 70b, each having the stator coupling hole 700b, are arranged along the rib 720b, it is not essential to form the coupling holes 700b along the rib 720b.

[0133] In addition, the rear wall portion of the tub 2 is formed with circumferential and radial reinforcing ribs 201 except for a region corresponding to the stepped regions of the bearing housing 7', for the sake of reinforcing the strength of the rear wall portion of the tub 2.

[0134] Alternatively, differently from the above described configuration of the stator coupling portion 7b of the bearing housing 7', although the stator coupling portion 7b of the bearing housing 7' is extended in a radial outward direction from the bearing supporting portion 7a in the form of a sleeve, it is branched into a plurality of portions spaced apart from one another by a regular distance in a circumferential direction, to obtain a radially distributed structure.

[0135] In the present embodiment, as a result of providing the bearing housing 7' with the coupling bosses 70b having the stator coupling holes 700b, it is unnecessary to perforate coupling holes in the tub 2.

[0136] Specifically, according to the above described configuration of the present embodiment, the stator 6 is secured to the rear wall portion of the tub 2 as it is bolted to the stator coupling holes 700b of the coupling bosses 70b provided at the stator coupling portion 7b of the bearing housing 7' that was previously embedded in the rear wall portion of the tub 2.

[0137] Near some of the coupling holes 700b of the stator coupling portion 7b are formed the positioning recesses 710b corresponding to the positioning protrusions formed at the insulator of the stator 6. With the provision of the positioning means, the stator 6 can be coupled to the rear wall portion of the tub 2 with an improved workability.

[0138] Preferably, the positioning recesses 710b, which are formed at the stator coupling portion 7b of the bearing housing 7', is configured so that it is exposed to the outside rather than being covered with a resin material. Conversely, if the positioning recesses are formed at the insulator of the stator 6, the stator coupling portion 7b of the bearing housing 7' may be formed with the positioning protrusions.

[0139] Hereinafter, a drum type washing machine according to a third embodiment of the present invention will be described in detail. Similarly, the description of the same configuration as that of the above described first and second embodiments will be omitted.

[0140] FIG. 14 is a sectional view illustrating a drive unit of a drum type washing machine according to the present embodiment.

[0141] The present embodiment has a feature in that a supporter is interposed between the rear wall portion of the tub and the stator. Here, the supporter serves not only to reinforce the rigidity of the rear wall portion of the tub, but also to allow the stator to be more strongly secured to the rear wall portion of the tub.

[0142] Accordingly, the washing machine according to the present embodiment comprises the tub 2 installed in the cabinet (not shown) and used to receive wash water therein, the drum 3 rotatably provided in the tub 2 and adapted to wash laundry received therein as it is rotated, the shaft 4 penetrated through the tub 2 and connected to the drum 3, the shaft 4 being adapted to transmit the drive force of the motor 5 to the drum 3, the stator 14 having the winding portions around which the coils are wound, the stator 14 being coupled fixedly to the rear wall portion of the tub 2, and the supporter interposed between the rear wall portion of the tub 2 and the stator 14 and adapted to increase the coupling strength between the tub 2 and the stator 14.

[0143] In the present embodiment, the metallic bearing housing 8 may be integrally formed with the rear wall surface 200 of the tub 2 via insert molding, simultaneously with the injection molding of the plastic tub 2.

[0144] Now, the supporter 27 of the present embodiment will be described in more detail.

[0145] The supporter 27 is interposed between the rear wall portion of the tub 2 and the stator 14, more particularly, between the rear wall surface 200 of the tub 2 and the stator 14. The supporter 27 has approximately the same outer contour as that of the rear wall surface 200 of the tub 2 and is secured to the rear wall surface 200 of the tub 2 when the stator 14 is coupled to the tub 2. Thereby, the supporter 27 serves to support the stator 14 while maintaining the stator 14 coaxially with the tub 2.

[0146] The supporter 27 has a front end coming into close contact with an inner surface of a rib 203 that is provided at a side of the rear wall surface 200 of the tub 2. A rear end of the supporter 27 is configured to come into close contact with an outer circumference of the rear end of the bearing housing 7', which is exposed to the outside without being surrounded by the hub 132 of the rotor frame provided at the center of the rear wall surface 200 of the tub 2.

[0147] Now, a drum type washing machine according to a fourth embodiment of the present invention will be described in detail with reference to FIG. 15.

[0148] The present embodiment has a feature in that a distance regulation washer is provided in addition to the configuration of the above described fourth embodiment. The distance regulation washer is interposed between the supporter and the stator and adapted to regulate a distance between the tub and the stator.

[0149] More specifically, in the present embodiment, the distance regulation washer 500 may be interposed between the supporter 27 and the stator 14 coupled to the supporter 27 and adapted to regulate a distance between the tub 2 and the stator 14. Preferably, the distance regulation washer 500 has an annular form suitable to stably separate the stator 14 from the tub 2. The distance regulation washer 500 may be formed, in a circumferential direction thereof, with a plurality of coupling holes. Accordingly, the distance regulation washer 500 performs the function of allowing the stator 14 to be coupled to the tub 2 with a predetermined distance therebetween.

[0150] Generally, the size of the tub and consequently, the capacity of the motor may be changed according to diversified capacities of washing machines. Also, the capacity of the motor is mainly determined by the magnitude of current applied to the motor. Accordingly, it can be said that the stator is the most important factor of determining the capacity of the motor. Although it is preferable to standardize the size of the rotor in views of price saving for the sake of mass production, this has an essential necessity for guaranteeing the flexible coupling of the motor even if the size of the stator is changed.

[0151] For this reason, if a small size stator is used, the distance regulation washer 500 has to be used to prevent the rotor from coming into contact with the rear wall portion of the tub when the stator is coupled with the rotor.

[0152] It will be apparent to those skilled in the art that various modifications and variations, related to the size, shape, and material of the constituent elements, can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A washing machine comprising: a tub for receiving wash water therein; a drum rotatably disposed in the tub and adapted to wash laundry received therein; a shaft penetrated through the tub to thereby be connected to the drum, the shaft being adapted to transmit a drive force of a motor to the drum; a stator coupled fixedly to a rear wall portion of the tub; and a rotor including at least one magnet, a back yoke defining a magnetic path, and a rotor frame rotatably disposed at the outside of the stator, the rotor frame being connected to the shaft so as to transmit a rotating force of the rotor to the shaft, wherein the rotor frame comprises a side wall portion and a rear wall portion, and is made of an aluminum material.

2. The washing machine according to claim 1, wherein the rotor frame is formed by die casting, and the side wall portion and the rear wall portion of the rotor frame are integrally formed with each other.

3. The washing machine according to claim 2, wherein the rear wall portion of the rotor frame is provided, at a center position thereof, with a connector, which is serration-coupled onto an outer circumference of the shaft and adapted to transmit the rotating force of the rotor to the shaft.

4. The washing machine according to claim 3, wherein the connector is made of an insulating material and integrally formed with the rotor frame by insert molding.

5. The washing machine according to claim 2, further comprising: a bearing housing provided between the rear wall portion of the tub and the stator and coupled fixedly to both the tub and the stator, the bearing housing receiving at least one bearing therein to rotatably support the shaft.

6. The washing machine according to claim 5, wherein the bearing housing is made of a metallic material.

7. The washing machine according to claim 2, wherein the side wall portion of the rotor frame is extended forward from an edge of the rear wall portion, and the side wall portion of the rotor frame is formed, in a circumferential direction thereof, with a ledge having a seating plane for supporting the magnet thereon.

8. The washing machine according to claim 2, wherein the stator comprises: a stator core including a winding portion around which a coil is wound and an annular body portion defining the magnetic path; and an insulator for insulating the stator core from the coil.

9. The washing machine according to claim 2, wherein the stator has thirty six poles, and the rotor has forty eight poles.

10. The washing machine according to claim 2, wherein the back yoke is attached to an inner surface of the side wall portion of the rotor frame in a circumferential direction by use of an adhesive, and the magnet is attached to an inner surface of the back yoke in a circumferential direction by use of an adhesive.