Drum type washing machine having a driving unit

Structure of driving unit in a drum type washing machine including a tub mounted inside of a cabinet, a drum mounted inside of the tub, a shaft connected to the drum mounted inside of the tub for transmission of a driving force from a motor to the drum, a front bearing and a rear bearing mounted on an outer circumference of the shaft at opposite end portions thereof respectively, a bearing housing built in a central portion of a rear wall of the tub for supporting the front bearing, a rotor composing the motor together with the rotor, and coupled to the rear end portion of the shaft, a stator fixed to the tub rear wall inward of the rotor to compose the motor together with the rotor, a connector serration coupled to the outer circumference of the shaft in front of the rear bearing and fixed to the rotor, for transmission of a rotating power from the rotor to the shaft, and a bearing bracket fixed to the rear wall of the tub to cover an outside of the rotor and support the rear bearing, thereby reducing noise, repair and power loss, by improving a structure of a driving unit, improving a product reliability, by improving a washing capability, and improving a productivity by improving workability in fabrication of components of the driving unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a drum type washing machine, and more particularly, to a structure of a driving unit in a drum type washing machine.

2. Background of the Invention

In general, a drum type washing, making washing by using friction between a drum rotated by a motor and laundry in a state detergent, washing water, and the laundry are introduced into the drum, provides effects of beating and rubbing washing, but gives almost no damage to the laundry, and shows no entangling of the laundry. A structure of a related art drum washing machine will be explained with reference toFIG. 1.FIG. 1illustrates a longitudinal section of a related art drum type washing machine, provided with a tub2mounted inside of a cabinet1, a drum3rotatably mounted on a central portion of inside of the tub2. There is a motor5aunder the tub2connected with a pulley18. There is a drum shaft connected to a rear of the drum3, to which a drum pulley19is coupled. And, the drum pulley19on the drum shaft and the motor pulley18connected to the motor5aare connected by a belt20for transmission of power. And, there is a door21in a front part of the cabinet1, with a gasket22between the door21and the tub2. There is a hanging spring between an inside of an upper portion of the cabinet1and an outside of an upper portion of the tub2, and a friction damper24between an inside of a lower portion of the cabinet1and a lower side of an outside of the tub2for damping vibration of the tub2generated during spinning.

However, the related art washing machine has the following disadvantages since driving power of the motor5ais transmitted to the drum3through the motor pulley18, and the drum pulley19, and the belt20connecting the motor pulley18and the drum pulley19.

First, there is a loss of energy in a course of driving power transmission because the driving power is transmitted from the motor5ato the drum3, not directly, but through the belt20wound around the motor pulley18and the drum pulley19.

And, the driving power transmission from the motor5ato the drum3, not directly, but through many components, such as the belt20, the motor pulley18, and the drum pulley19, causes much noise in the course of power transmission.

The lots of components required for transmission of driving power from the motor5ato the drum3, such as the motor pulley18, the drum pulley19and the belt20, require many assembly man-hours. And, the more the number of components required for transmission of driving power from the motor5ato the drum3, the more number of spots which require repair, and the more frequent at which repair required.

In summary, the indirect driving power transmission from the motor5ato the drum3through the motor pulley, the drum pulley, and the belt requires many repair, has much noise, waste of energy, and results in a deterioration of a washing capability.

Moreover, the tub2of stainless steel in general in the related art drum washing machine is expensive, has a poor formability, and is heavy.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a structure of a driving unit in a drum type 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 structure of driving unit in a drum type washing machine, which can reduce noise, repair and waste of energy, and moreover, improve washing capability.

Another object of the present invention is to provide a structure of driving unit in a drum type washing machine, which has an improved supporting force.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the structure of a driving unit in a drum type washing machine having a tub mounted in a cabinet, a drum mounted in the tub, a shaft fixed to the drum for transmission of driving power from the motor to the drum, and bearings mounted on an outer circumference of the shaft at opposite end portions thereof, includes a metallic bearing housing at a central portion of a rear wall of the tub for supporting the bearings mounted on the outer circumferences of opposite end portions of the shaft.

In other aspect of the present invention, there is provided a structure of driving unit in a drum type washing machine including a tub mounted inside of a cabinet, a bearing housing built in a central portion of a rear wall of the tub for supporting a bearing therein, a shaft connected to a drum mounted inside of the tub for transmission of a driving force from a motor to the drum, bearings mounted on an outer circumference of the shaft at opposite end portions thereof respectively, a rotor coupled to a rear end of the shaft, a stator provided inward of the rotor fixed to the tub rear wall, a connector provided between the shaft and the rotor for transmission of a rotating force from the rotor to the shaft for rotating the shaft and the rotor together, and a supporter fitted between the rear wall of the tub and the stator for supporting the stator and maintaining a concentricity when the stator is mounted to the tub rear wall.

In another aspect of the present invention, there is provided a structure of driving unit in a drum type washing machine including a tub of plastic mounted inside of a cabinet, a metallic bearing housing inserted and built in a central portion of a rear wall of the tub having steps of “┐” and “└” forms on an inner circumference for supporting bearings therein, a shaft connected to a drum mounted inside of the tub for transmission of a driving power from a motor to the drum, having a front end portion fixed to a spider in the drum rear wall, a brass bushing press fit on a region of the shaft from a portion exposed in rear of the spider to the front bearing for prevention of rusting of the shaft, and steps on an outer circumference thereof for fixing mounting positions of the front bearing and the rear bearing on the shaft, bearings mounted on the outer circumference of the shaft at opposite end portions thereof respectively, a rotor of steel or steel alloy plate coupled to the rear end portion of the shaft, including a bent portion formed along a circumference thereof having a setting surface for supporting magnets fitted to an inside of a front portion of a sidewall extended forward from a periphery of a rear wall, and a hub at a center of the rear wall having a through hole for a fastening member, such as a bolt, for coupling the rotor to the shaft, a plurality of cooling fins formed around the hub in a radial direction each with a length for blowing air toward the stator when the rotor is rotated for cooling down a heat generated at the stator, an embossing between adjacent cooling fins on the rear wall of the rotor for reinforcing the rotor, and a drain hole in each of the embossings, for drain of water, a stator composing the motor together with the rotor, fixed to the tub rear wall inward of the rotor, a connector of plastic provided between the shaft and the rotor for transmission of a rotating force from the rotor to the shaft for rotating the shaft and the rotor together, and a supporter fitted between the rear wall of the tub and the stator for supporting the stator and maintaining a concentricity when the stator is mounted to the tub rear wall.

In further aspect of the present invention, there is provided a structure of driving unit in a drum type washing machine including a tub mounted inside of a cabinet, a drum mounted inside of the tub, a shaft connected to the drum mounted inside of the tub for transmission of a driving force from a motor to the drum, a front bearing and a rear bearing mounted on an outer circumference of the shaft at opposite end portions thereof respectively, a bearing housing built in a central portion of a rear wall of the tub for supporting the front bearing, a rotor composing the motor together with the rotor, and coupled to the rear end portion of the shaft, a stator fixed to the tub rear wall inward of the rotor to compose the motor together with the rotor, a connector serration coupled to the outer circumference of the shaft in front of the rear bearing and fixed to the rotor, for transmission of a rotating power from the rotor to the shaft, and a bearing bracket fixed to the rear wall of the tub to cover an outside of the rotor and support the rear bearing.

In a still further aspect of the present invention, there is provided a structure of driving unit in a drum type washing machine including a tub of plastic mounted inside of a cabinet, a metallic bearing housing inserted to built in a central portion of a rear wall of the tub having steps on an inner circumference for supporting bearings therein, a shaft connected to a drum mounted inside of the tub for transmission of a driving power from a motor to the drum, having a front end portion fixed to a spider in the drum rear wall and a brass bushing press fit on a region of the shaft from a portion exposed in rear of the spider to the front bearing for prevention of rusting of the shaft, bearings mounted on the outer circumference of the shaft at opposite end portions thereof respectively, a rotor of steel or steel alloy plate coupled to the rear end portion of the shaft, including a bent portion formed along a circumference thereof having a setting surface for supporting magnets fitted to an inside of a front portion of a sidewall extended forward from a periphery of a rear wall, and a hub at a center of the rear wall having a through hole for a fastening member, such as a bolt, for coupling the rotor to the shaft, a plurality of cooling fins formed around the hub in a radial direction each with a length for blowing air toward the stator when the rotor is rotated for cooling down a heat generated at the stator, an embossing between adjacent cooling fins on the rear wall of the rotor for reinforcing the rotor, and a drain hole in each of the embossings, for drain of water, a stator composing the motor together with the rotor, fixed to the tub rear wall inward of the rotor, a connector of plastic provided between the shaft and the rotor for transmission of a rotating force from the rotor to the shaft for rotating the shaft and the rotor together, a supporter fitted between the rear wall of the tub and the stator for supporting the stator and maintaining a concentricity when the stator is mounted to the tub rear wall, and a bearing bracket fixed to the rear wall of the tub to cover an outside of the rotor and support the rear bearing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. A first preferred embodiment of the present invention will be explained in detail with reference toFIGS. 2A˜8.FIG. 2Aillustrates a longitudinal section of a drum type washing machine in accordance with a first preferred embodiment of the present invention,FIG. 2Billustrates a detailed enlarged view of “A” part inFIG. 2A.FIG. 3illustrates a perspective view with a partial cut away view of the rotor inFIG. 2.FIG. 4illustrates an enlarged perspective view of “B” part inFIG. 3.FIG. 5illustrates a perspective view of a bottom inFIG. 3.FIG. 6illustrates a perspective view of the stator inFIG. 2,FIG. 7illustrates a perspective view of the connector inFIG. 2, andFIG. 8illustrates a perspective view of a bottom inFIG. 7.

The drum type washing machine in accordance with a first preferred embodiment of the present invention includes a tub2of plastic mounted inside of the cabinet1, a drum3mounted in the tub2, a shaft4fixed to the drum3for transmission of driving power from a motor5to the drum3, bearings6aand6bfitted on outer circumference of the shaft4at both ends thereof, and bearing housings7of metal fitted to support the bearings6aand6bat a central portion of a rear wall200of the tub2. The bearing housing7of metal is formed as a unit with the tub rear wall200by an inserted injection molding in the injection molding of the tub2of plastic. The bearing housing7is preferably formed of aluminum. The bearing housing7has steps8aand8bfor holding the front bearing6aand the rear bearing6bfitted in inner circumferences of the bearing housing7for preventing the bearings6aand6bfrom being fallen off. Of the steps8aand8bformed on the inner circumferences of the bearing housing7, the front step8ahas a form of “┐” for supporting a rear end portion of the front bearing6afitted to a front end of an outer circumference of the shaft4, and the rear step8bhas a form of “└” for supporting a front end portion of the rear bearing6bfitted to a rear end portion of the shaft4. And, there are positioning steps400aand400bon outer circumferences of the shaft4disposed inside of the bearing housing7which transmits driving power from the motor5to the drum3, for fixing mounting positions of the front bearing6aand the rear bearing6bon the shaft4. A front end of the shaft4is coupled to a spider10in a rear wall of the drum3, a region of the shaft4from a portion exposed in rear of the spider10to the front bearing6ahas a bushing11of brass press fit thereon for prevention of rusting, and there is a sealing member12on an outer surface of the bushing11for preventing ingress of water toward the bearing. There is a rotor13of a direct coupling type motor5fixed to a center of a rear end of the shaft4, and a stator14of a crown form, consisting the direct coupling type motor5together with the rotor13, fixed to the rear wall200inside of the rotor13.

Referring toFIGS. 3˜5, the rotor13of steel or steel alloy plate includes a bent portion formed along a circumference thereof having a setting surface130for supporting magnets13cfitted to an inside of front of a sidewall13bextended forward from a periphery of a rear wall13a, and a hub132at a center of the rear wall13ahaving a through hole131for fastening members15a, such as bolts, for coupling the rotor13to the shaft4. An overall form of the rotor13is preferably formed by press forming. There are a plurality of cooling fins133each formed to have a preset length in a radial direction around the hub132of the rotor13for blowing air toward the stator14during rotation of the rotor13for cooling heat generated at the stator14. The cooling fins133are formed by lancing, to bend the cooling fins133at a right angle to the rear wall toward the opening to leave through holes134for ventilation. There is an embossing135between adjacent cooling fins133with a drain hole136therein for draining water. There are fastening holes137for fastening a connector16to the rotor13and positioning holes138for positioning an assembly position of the connector16around the through hole131in the hub132of the rotor13at fixed intervals, which connector16is serration coupled to an outer circumference of a rear end portion of the shaft4exposed to rear of the rear bearing6b. The connector16is formed of resin having a vibration mode different from the rotor13of steel or steel alloy plate, and also serves as a bushing for the rotor13. As shown inFIGS. 2B,7and8, the connector16has fastening holes162to correspond to the fastening holes137in the hub132of the rotor13around a circumferential direction of the a peripheral region and a dowel pin160between adjacent fastening holes162as a unit with the connector16for insertion in the positioning hole138in the rotor13for self alignment of the fastening holes137and162in the rotor13and the connector16, respectively. The connector16has a serration in an inside circumference of the hub163matched to the serration in the rear end of the shaft4, and reinforcing ribs161on outer circumference of the hub163for reinforcing the hub163. There is a hub201on the rear wall200of the tub2having the bearing housing7inserted therein when the tub is injection molded, and fastening bosses202on an outer side of the hub201along a circumferential direction at fixed intervals for fastening the stator14to the rear wall200of the tub2. There is a supporter17between the rear wall200of the tub2and the stator14, of a form almost identical to an outline of the tub rear wall200, fixed to the tub rear wall200when the stator14is assembled for supporting the stator14and maintaining concentricity of the stator14. The supporter17has a fore end brought into a close contact with an inside of ribs203at one side of the tub rear wall200, and a rear end brought into a close contact with an outer circumference of a rear end of the bearing housing7which is not enclosed by the hub132, but exposed. In the meantime, as shown inFIGS. 2B and 6, the stator14includes a magnetic core145of segregated layers of magnetic material, a frame140of resin coated on the magnetic core145, a coil142wound around each of winding parts141on an outer circumference of the frame140, and fastening ribs143on an inside of the frame140for fastening the stator14to the tub rear wall200.

The operation of the driving unit in a drum type washing machine in accordance with a first preferred embodiment of the present invention will be explained. Upon causing rotation of the rotor13by making a current to flow to the coils142of the stator14in a sequence under the control of a motor driving controller(not shown) fitted on a panel, the shaft4serration coupled with the connector16fixed to the rotor is rotated, together with the drum3as the power is transmitted to the drum3through the shaft4.

In the meantime, the drum type washing machine having the driving unit of the present invention applied thereto serves as follows. The tub2of the drum type washing machine of the present invention, formed of a plastic with an excellent heat resistance, is light and has a good formability as the tub2is injection molded. Since the bearing housing7in the drum type washing machine of the present invention is formed of a metal, such as aluminum and the like, the bearing housing7is applicable to a drum type washing machine having a drying cycle as the bearing housing shows no thermal deformation. And, since the metallic bearing housing7of the present invention is formed integrated with the tub2by inserting the bearing housing7in the hub201on the tub rear wall200before the tub2of plastic is injection molded, a separate step for assembling the bearing housing7to the tub rear wall200can be omitted, which simplifies an assembly process, that reduces assembly man-hours. The “┐” form of the step8ain a front portion of an inner circumference of the bearing housing7and the “└” form of the step8bin a rear portion of an inner circumference of the bearing housing7permit to support a rear end of the front bearing6aand a fore end of the rear bearing6bmounted on outer circumference of the shaft4at both end portions thereof. That is, the steps8aand8bon inner circumferences of the metallic bearing housing7on both sides thereof prevent both bearings6aand6bfrom being fallen off the bearing housing7. The positioning steps400aand400bon outer circumferences of the shaft4at front and rear portions thereof permit easy positioning of the front bearing6aand the rear bearing6bon the shaft4in the assembly. The front end portion of the shaft4is coupled to the spider10in the rear wall, and the brass bushing11press fit to the region from the exposed portion outside of the spider10of the shaft4to the front bearing6aprevents rusting of the shaft4. The sealing member12outside of the bushing11prevents ingress of water toward the bearing.

In the meantime, the rotor13of the direct coupling type motor5is mounted on a center of the rear end portion of the shaft4, with the stator14disposed on inner side of the rotor, wherein the bend part having the magnet setting surface130is formed along a circumferential direction of the sidewall13bextended forward from a periphery of the rear wall13aof the rotor13, for supporting the magnets13cwhen the magnets13care fitted to an inside surface of the rotor13, to fabricate the rotor with easy. The through hole131of the hub132at a center of the rear wall13aof the rotor13permits the fastening member15b, such as a bolt or the like, to pass therethrough for fastening the rotor13to the shaft4, and the plurality of cooling fins133around the hub132of the rotor13in a radial direction with a length blow air toward the stator14during rotation of the rotor13for cooling down a heat generated at the stator14. The cooling fins133are formed by lancing, to direct toward the opening of the rotor13, and to leave through holes134for ventilation. The rotor13of steel or steel alloy plate is formed by pressing, which shortens a fabrication time period, that improves a productivity. The embossing135between the adjacent cooling fins133of the rear wall13aof the rotor13improves an overall strength of the rotor13, and the drain hole136in the embossing135drains water.

In the meantime, the fastening holes137for fastening the connector and the positioning holes138for fixing an assembly position of the connector16around the through hole131in the hub132of the rotor13permits an easy assembly of the connector16to the rotor, which connector16is serration coupled to the outer circumference of the rear end portion of the shaft4exposed to rear of the rear bearing6b. That is, once the dowel pins160on the connector16are inserted in the positioning holes138in the rotor13, the fastening holes137and162in the rotor13and the connector16are matched automatically, and by fastening the fastening members15cthrough the fastening holes137and162in the rotor13and the connector16, the connector16and the rotor13can be assembled with easy. The connector16serves to damp vibration from the rotor13to the shaft4as the connector16injection molded of a resin has a different vibration mode from the rotor13of steel or steel alloy plate. The serration164in the inner circumference of the hub163of the connector16is fit to the serration400in the rear end portion of the shaft4, to transmit the rotating force of the rotor13to the shaft, directly. The reinforcing ribs161on an outer circumference of the hub163of the connector16reinforce the hub163.

In the meantime, the fastening bosses202along a circumference on an outer side of the hub201on the rear wall200of the tub2at fixed intervals permits to fix the stator14to the rear wall200of the tub2by using the fastening boss202. The supporter17between the rear wall200of the tub2and the stator14having a form almost identical to the outline of the rear wall200for being fixed to the rear wall200of the tub2when the stator14is fastened permits the stator14being supported and maintained of concentricity. That is, once the supporter17is fastened to the fastening bosses204on the tub rear wall200, the fore end of the supporter17is brought into close contact with an inside surface of the ribs203at one side of the tub rear wall200and the rear end of the supporter17is brought into close contact with the outer circumference of the rear end portion of the bearing housing7at a central portion of the tub rear wall200, which can not be enclosed, but exposed, by the hub132, such that the supporter17supports the stator14as well as maintains a concentricity of the stator14.

The structure of a driving unit in a drum type washing machine in accordance with a first preferred embodiment of the present invention has the following advantages.

The motor direct coupling structure of the drum type washing machine in accordance with a first preferred embodiment of the present invention permits to reduce repair, and power loss.

The bearing housing of metal in the drum type washing machine in accordance with a first preferred embodiment of the present invention shows no thermal deformation, that allows to apply to a product having a drying function.

The rotor of steel or steel alloy plate formed by pressing in the drum type washing machine in accordance with a first preferred embodiment of the present invention requires a very short fabrication time period, with an improved productivity, because the steel or steel alloy plate pressing has an excellent formability.

And, the magnet setting surface on the rotor of the present invention improves a workability in fitting the magnets, and the drain holes, the cooling fins, and the through holes provided to the rotor can prevent overheating of the motor, improve a reliability of the motor, and prolong a lifetime of the motor.

And, the connector having a vibration mode different from the rotor in the drum type washing machine of the present invention can attenuate the vibration transmitted from the rotor to the shaft, and the supporter can support the stator and maintain a concentricity of the stator.

A driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention will be explained with reference toFIGS. 3˜9, in detail.FIG. 9illustrates a longitudinal section of a driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention. The rotor, the stator and the connector in the second preferred embodiment of the present invention are identical to those of the first embodiment, to which the same names and reference symbols are given, and will be explained with reference toFIGS. 3˜8.

The drum type washing machine in accordance with a second preferred embodiment of the present invention includes a tub2mounted inside of a cabinet1, a drum3mounted inside of the tub2, a shaft4connected to the drum mounted inside of the tub3for transmission of a driving force from the motor5to the drum, a front bearing6aand a rear bearing6bmounted on outer circumferences of the shaft4at both end portions thereof respectively, a bearing housing7built in a central portion of the rear wall200of the tub3for supporting the front bearing6a, a rotor13coupled to the shaft4, a stator14provided inward of the rotor13coupled to the tub rear wall200, a connector16serration coupled to an outer circumference of the shaft4in front of the rear bearing6band fixed to the rotor13for transmission of a rotating force of the rotor13to the shaft4, a supporter17fitted between the rear wall200of the tub2and the stator14for supporting the stator and maintaining a concentricity when the stator is mounted to the tub rear wall200, and a bearing bracket9fixed to the tub rear wall200for covering outside of the rotor13and supporting the front end portion of the rear bearing6b. The tub2is formed of plastic, and has an opened front and a closed rear wall200of which thickness is greater than a thickness of a sidewall, and the bearing housing7at the central portion of the rear wall200of the tub2is formed of a metal, wherein the bearing housing7is insert injection molded when the plastic tub2is injection molded, such that the bearing housing7is integrated with the tub rear wall200. The bearing housing7is preferably formed of an aluminum alloy.

In the meantime, there is a step7aon an inner circumference of the metallic bearing housing7for supporting the front bearing6ato prevent the front bearing7from being fallen off the bearing housing7. The step7aon the inner circumference of the bearing housing7has a form of “┐” for having a structure which supports a rear end portion of the front bearing6amounted on a front end portion of the shaft4. The front end portion of the shaft4is fixed to a spider10in the rear wall200of the drum3, a region of the shaft4from a portion exposed in rear of the spider10to the front bearing6ahas a bushing11of brass press fit thereon for prevention of rusting, and there is a sealing member12on an outer surface of the bushing11for preventing ingress of water toward the front bearing6a. There connector16is serration coupled to the rear end portion of the shaft4for connection between the rotor13of the direct coupling type motor5and the shaft4, the rotor13is fixed to the connector16with fastening members15c, and the stator14, forming the direct coupling type motor together with the rotor13, is fixed to the rear wall200of the tub2inward of the rotor13. As shown inFIGS. 3˜5, the rotor13of steel or steel alloy plate includes a bend part having a magnet setting surface130formed along a circumferential direction of a sidewall13bextended forward from a periphery of the rear wall13aof the rotor13, for supporting magnets13cfitted to a front portion of an inside surface of the rotor13, and a hub132having a through hole131at a center of the rear wall13aof the rotor13so that a fastening member15a, such as a bolt or the like, can pass through for coupling the rotor13to the shaft4. An overall form of the rotor13is preferably formed by pressing. There are a plurality of cooling fins133each formed to have a preset length in a radial direction around the hub132of the rotor13for blowing air toward the stator14during rotation of the rotor13for cooling heat generated at the stator14. The cooling fins133are formed by lancing, to bend the cooling fins133at a right angle to the rear wall13atoward the opening to leave through holes134for ventilation. There is an embossing135between adjacent cooling fins133with a drain hole136therein for draining water. There are fastening holes137for fastening a connector16to the rotor13and positioning holes138for positioning an assembly position of the connector16around the through hole131in the hub132of the rotor13at fixed intervals, which connector16is serration coupled to an outer circumference of a rear end portion of the shaft4exposed in rear of the rear bearing6b. The connector16is formed of resin having a vibration mode different from the rotor13of steel or steel alloy plate. As shown inFIGS. 7˜9, the connector16has fastening holes162to correspond to the fastening holes137in the hub132of the rotor13around a circumferential direction of the a peripheral region and a dowel pin160between adjacent fastening holes162as a unit with the connector16for insertion in the positioning hole138in the rotor13for self alignment of the fastening holes137and162in the rotor13and the connector16, respectively. The connector16has a serration in an inside circumference of the hub163matched to the serration in the rear end of the shaft4, and reinforcing ribs161on outer circumference of the hub163for reinforcing the hub163. There is a hub201on the rear wall200of the tub2having the bearing housing7inserted therein when the tub is injection molded, and fastening bosses202on an outer side of the hub201along a circumferential direction at fixed intervals for fastening the stator14to the rear wall200of the tub2. There is a supporter17between the rear wall200of the tub2and the stator14, of a form almost identical to an outline of the rear wall200, fixed to the tub2rear wall200when the stator14is assembled for supporting the stator14and maintaining concentricity of the stator14. Once the supporter17is fastened to the support fastening bosses204, a fore end of the supporter17is brought into close contact with an inside of ribs203at one side of the tub rear wall200, and a rear end thereof is brought into close contact with an outer circumference of a rear end of the bearing housing7which is not enclosed by the hub132, but exposed, thereby the supporter17supporting the stator14and maintaining a concentricity of the stator. In the meantime, as shown inFIGS. 3 and 6, the stator14includes a ring formed frame140, a coil142wound around each of winding parts141on an outer circumference of the frame140, and fastening ribs143on an inside of the frame140for fastening the stator14to the tub rear wall200.

In the meantime, referring toFIG. 9, there is an “└” formed step990bat an inner end portion of the bearing bracket9fixed to the tub rear wall200to cover an outer side of the rotor13. And, there is a rear bearing fixing member15bat an rear end of the shaft4for supporting a rear surface of the shaft4to prevent the rear bearing from being fallen off the shaft4.

The operation of the driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention will be explained. Upon causing rotation of the rotor13by making a current to flow to the coils142of the stator14in a sequence under the control of a motor driving controller(not shown) fitted on a panel, the shaft4serration coupled with the connector16fixed to the rotor is rotated, together with the drum3as the power is transmitted to the drum3through the shaft4.

In the meantime, the drum type washing machine in accordance with the second preferred embodiment of the present invention driven thus serves as follows. Alike the first embodiment of the present invention, since the tub1is formed of a plastic with an excellent heat resistance, the tub1is light and has a good formability as the tub2is injection molded. Since the bearing housing7is formed of a metal, such as an aluminum alloy and the like, the bearing housing7is applicable to a drum type washing machine having a drying cycle as the bearing housing shows no thermal deformation. And, since the metallic bearing housing7is formed integrated with the tub2by inserting the bearing housing7in the hub201on the tub rear wall200before the tub2of plastic is injection molded, a separate step for assembling the bearing housing7to the tub rear wall200can be omitted, which simplifies an assembly process, that reduces assembly man-hours. The step7ain an inner circumference of a front portion of the bearing housing7in the second embodiment of the present invention supports a rear end of the front bearing6amounted on an outer circumference of the fore end portion of the shaft4. That is, the “┐” formed step7ain a front portion of an inner circumference of the metallic bearing housing7of the present invention permits to support the front bearing6awithout being fallen off the bearing housing7. And, the “└” formed step900bin an end portion of an inner circumference of the metallic bearing bracket9covering an outer side of the rotor13fixed to the tub rear wall200permits to support a front end of the rear bearing6bmounted on the rear end portion of the shaft4, and the rear bearing fixing member15bon the rear end surface of the shaft4prevents the rear bearing6bfrom being fallen off the shaft4.

In the meantime, in the second preferred embodiment of the present invention, since the front bearing6ais mounted in the bearing housing7having insert injection molded in the tub1, and the rear bearing6bis mounted in an inside of a center portion of the bearing bracket9, a distance between the front and rear bearings6aand6bon the shaft4becomes greater, between which the rotor is mounted. The greater distance between the front and rear bearings6aand6bpermits to withstand a load caused by imbalance of laundry in the drum1during spinning better, and a supporting force to the rotor13is enhanced as the rotor13of the motor is mounted between the front and rear bearings6aand6b. Alike the first preferred embodiment of the present invention, in the second preferred embodiment of the present invention, the brass bushing11press fit to the region from the exposed portion outside of the spider10of the shaft4to the front bearing6aprevents rusting of the shaft4. And, a likely, the sealing member12outside of the bushing11prevents ingress of water toward the bearing.

Alike the first preferred embodiment, as shown inFIGS. 3 to 6, the bend part having the magnet setting surface130is formed along a circumferential direction of the sidewall13bextended forward from a periphery of the rear wall13aof the rotor13, for supporting the magnets13cwhen the magnets13care fitted to an inside surface of the rotor13, to fabricate the rotor with easy. Alike the first preferred embodiment of the present invention, in the second preferred embodiment of the present invention, the plurality of cooling fins133around the hub132of the rotor13in a radial direction with a length blow air toward the stator14during rotation of the rotor13for cooling down a heat generated at the stator14. The cooling fins133are formed by lancing, to direct toward the opening of the rotor13, and to leave through holes134for ventilation. Since the rotor13is formed of steel or steel alloy plate by pressing, which shortens a fabrication time period significantly, a productivity is improved. The embossing135between the adjacent cooling fins133of the rear wall13aof the rotor13improves an overall strength of the rotor13, and the drain hole136in the embossing135drains water.

In the meantime, the fastening holes137for fastening the connector and the positioning holes138for fixing an assembly position of the connector16around the through hole131in the hub132of the rotor13permits an easy assembly of the connector16to the rotor, which connector16is serration coupled to the outer circumference of the rear end portion of the shaft4. That is, once the dowel pins160on the connector16are inserted in the positioning holes138in the rotor13, the fastening holes137and162in the rotor13and the connector16are matched automatically, and by fastening the fastening members15cthrough the fastening holes137and162, the connector16and the rotor13can be assembled with easy. The connector16serves to damp vibration from the rotor13to the shaft4as the connector16injection molded of a resin has a different vibration mode from the rotor13of steel or steel alloy plate. The serration164in the inner circumference of the hub163of the connector16is fit to the serration400in the rear end portion of the shaft4, to transmit the rotating force of the rotor13to the shaft, directly. The reinforcing ribs161on an outer circumference of the hub163of the connector16reinforce the hub163.

In the meantime, the fastening bosses202along a circumference on an outer side of the hub201on the rear wall200of the tub2at fixed intervals permits to fix the stator14to the rear wall200of the tub2by using the fastening boss202. The supporter17between the rear wall200of the tub2and the stator14having a form almost identical to the outline of the rear wall200for being fixed to the rear wall200of the tub2when the stator14is fastened permits the stator14being supported and maintained of concentricity. That is, the front end of the supporter17is brought into close contact with an inside surface of the ribs203at one side of the tub rear wall200and the rear end of the supporter17is brought into close contact with the outer circumference of the rear end portion of the bearing housing7at a central portion of the tub rear wall200, which can not be enclosed, but exposed, by the hub132, such that the supporter17supports the stator14as well as maintains a concentricity of the stator14.

The structure of a driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention has the following advantages.

The motor direct coupling structure of the drum type washing machine of the present invention permits to reduce repair, noise and power loss.

The bearing housing of metal in the drum type washing machine of the present invention shows no thermal deformation, that allows to apply to a product having a drying function.

The rotor of steel or steel alloy plate formed by pressing in the drum type washing machine of the present invention requires a very short fabrication time period, with an improved productivity, because the steel or steel alloy plate pressing has an excellent formability.

And, the magnet setting surface on the rotor of the present invention improves a workability in fitting the magnets, and the drain holes, the cooling fins, and the through holes provided to the rotor can prevent overheating of the motor, improve a reliability of the motor, and prolong a lifetime of the motor.

And, the connector having a vibration mode different from the rotor in the drum type washing machine of the present invention can attenuate the vibration transmitted from the rotor to the shaft, and the supporter can support the stator and maintain a concentricity of the stator.

Particularly, in the second preferred embodiment of the present invention, the greater distance between the front and rear bearings permits to withstand a load caused by imbalance of laundry in the drum1during spinning better, and a supporting capability to the rotor is enhanced as the rotor of the motor is mounted between the front and rear bearings.

Thus, by improving a structure of a driving unit of a drum type washing machine, the present invention can reduce noise, repair and power loss, by improving a washing capability, can improve a product reliability, and, by improving workability in fabrication of components of the driving unit, can improve a productivity.

It will be apparent to those skilled in the art that various modifications and variations can be made in the structure of a driving unit in a drum type 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.