Patent Publication Number: US-RE43196-E

Title: Structure of driving unit in drum type washing machine

Description:
This application is a Divisional Reissue application of Reissue application Ser. No. 11/043,912, filed Jan. 27, 2005, now U.S. Pat. No. Re. 41,621, which is a Reissue of U.S. Pat. No. 6,510,716. More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,510,716. The Reissue application numbers are Ser. No. 11/043,912 (the parent Reissue application), now U.S. Pat. No. Re. 41,621, Ser. Nos. 11/602,777, and 11/043,912 (the present application). 
     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 to  FIG. 1 .  FIG. 1  illustrates a longitudinal section of a related art drum type washing machine, provided with a tub  2  mounted inside of a cabinet  1 , a drum  3  rotatably mounted on a central portion of inside of the tub  2 . There is a motor  5 a under the tub  2  connected with a pulley  18 . There is a drum shaft  25  connected to a rear of the drum  3 , to which a drum pulley  19  is coupled. And, the drum pulley  19  on the drum shaft and the motor pulley  18  connected to the motor  5 a are connected by a belt  20  for transmission of power. And, there is a door  21  in a front part of the cabinet  1 , with a gasket  22  between the door  21  and the tub  2 . There is a hanging spring  23  between an inside of an upper portion of the cabinet  1  and an outside of an upper portion of the tub  2 , and a friction damper  24  between an inside of a lower portion of the cabinet  1  and a lower side of an outside of the tub  2  for damping vibration of the tub  2  generated during spinning. There is a detergent container  26  in the upper front of the cabinet  1 , and in the upper back of the cabinet  1  is a water supply valve  27  for supplying water to the detergent container. 
     However, the related art washing machine has the following disadvantages since driving power of the motor  5 a is transmitted to the drum  3  through the motor pulley  18 , and the drum pulley  19 , and the belt  20  connecting the motor pulley  18  and the drum pulley  19 . 
     First, there is a loss of energy in a course of driving power transmission because the driving power is transmitted from the motor  5 a to the drum  3 , not directly, but through the belt  20  wound around the motor pulley  18  and the drum pulley  19 . 
     And, the driving power transmission from the motor  5 a to the drum  3 , not directly, but through many components, such as the belt  20 , the motor pulley  18 , and the drum pulley  19 , causes much noise in the course of power transmission. 
     The lots of components required for transmission of driving power from the motor  5 a to the drum  3 , such as the motor pulley  18 , the drum pulley  19  and the belt  20 , require many assembly man-hours. And, the more the number of components required for transmission of driving power from the motor  5 a to the drum  3 , the more number of spots which require repair, and the more frequent at which repair required. The imbalance caused by the motor mounted to a lower part of rear of the tub  2  causes heavy vibration when the motor is rotated. Consequently, there is a weight balancer of metal or cement separately provided to an opposite position of the motor for system balancing. 
     In summary, the indirect driving power transmission from the motor  5 a to the drum  3  through 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. 
     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, in which the motor is coupled to the drum directly for reducing vibration, and either reducing a weight of the weight balancer or remove the weight balancer completely. 
     Another object of the present invention is to provide a structure of driving unit in a drum type washing machine, which can reduce waste of energy by employing a BLDC motor that has a good energy efficiency. 
     Other object of the present invention is to provide a structure of driving unit in a drum type washing machine, which involves no deformation of the rotor even if the rotor rotates at a high speed. 
     Further object of the present invention is to provide a structure of driving unit in a drum type washing machine, which permits an easy assembly of the drum washing machine. 
     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these and other advantages and in accordance with the purposes of the present invention, as embodied and broadly described, the structure of a driving unit in a drum type washing machine includes a tub for storing washing water, a drum rotatably mounted inside of the tub disposed horizontal to the ground, or with an angle to the ground for accommodating laundry therein, a shaft connected, through the tub, to the drum mounted inside of the tub, for transmission of a driving force of the motor to the drum, bearing fitted each onto an outer circumference of the shaft for supporting the shaft, a bearing housing having stator fastening bosses disposed at fixed intervals along a circumference of a central portion thereof, for supporting the bearings, a stator having a plurality of magnetic cores formed by stacking magnetic laminations, each having a salient pole projected outward and a plurality of coils each wound around a respective one of the salient poles, and a cup formed rotor having a rotor body and permanent magnets, the rotor by comprising a sidewall and a rear wall to cover an outer circumference and a bottom of the stator, the permanent magnets fitted to the side wall, ad a connecter connecting the rotor and the shaft. 
     Preferably, the salient poles of the stator are projected outward in a radial direction with respect to a central longitudinal axis of the stator. Preferably, the stator further comprises a frame of insulating material for covering top and bottom surfaces of a magnetic core assembly of the magnetic cores. And preferably the stator further comprises a plurality of fastening ribs projected inward, each with a fastening hole for fixing the stator to the bearing housing. More preferably the fastening ribs are projected inward in the radial direction. And more preferably the fastening ribs are formed as one unit with the frame. 
     Preferably the rotor body is formed of magnetic material such as iron or iron alloy, which enables the side wall of the rotor body to serve as a back yoke that forms a magnetic flux path. Preferably the rear wall of the rotor body is formed as one unit with the sidewall. Preferably the permanent magnets are fitted to a setting surface of an “L” formed bent portion of the side wall. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention: 
       In the drawings: 
         FIG. 1  illustrates a longitudinal section of a related art drum type washing machine; 
         FIG. 2A  illustrates a longitudinal section of a drum type washing machine in accordance with a first preferred embodiment of the present invention; 
         FIG. 2B  illustrates a detailed enlarged view of “A” part in  FIG. 2A ; 
         FIG. 2C  illustrates a detailed enlarged view of “B” part in  FIG. 2B ; 
         FIG. 3  illustrates a right side view of  FIG. 2B  having a motor removed therefrom; 
         FIG. 4  illustrates a perspective view showing the rotor in  FIGS. 2A˜2C  with a partial cut away view; 
         FIG. 5  illustrates an enlarged perspective view of “C” part in  FIG. 4 ; 
         FIG. 6  illustrates a perspective view of a bottom of  FIG. 4 ; 
         FIG. 7  illustrates a perspective view of the stator in  FIG. 2 ; 
         FIG. 8  illustrates a perspective view of the connector in  FIG. 2 ; 
         FIG. 9  illustrates a perspective view of a bottom of  FIG. 8 ; 
         FIG. 10  illustrates a longitudinal section of key parts of a structure of a driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention; 
         FIG. 11  illustrates a right side view of  FIG. 10  having a motor removed therefrom; 
         FIG. 12  illustrates a longitudinal section of key parts of a structure of a driving unit in a drum type washing machine in accordance with a third preferred embodiment of the present invention; and, 
         FIG. 13  illustrates a longitudinal section of key parts of a structure of a driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention. 
     
    
    
     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 drum type washing machine in accordance with a first preferred embodiment of the present invention will be explained with reference to  FIGS. 2A-9 .  FIG. 2A  illustrates a longitudinal section of a drum type washing machine in accordance with a first preferred embodiment of the present invention,  FIG. 2B  illustrates a detailed enlarged view of “A” part in  FIG. 2A ,  FIG. 2C  illustrates a detailed enlarged view of “B” part in  FIG. 2B ,  FIG. 3  illustrates a right side view of  FIG. 2B  having a motor removed therefrom,  FIG. 4  illustrates a perspective view showing the rotor in  FIGS. 2A-2C  with a partial cut away view,  FIG. 5  illustrates an enlarged perspective view of “C” part in  FIG. 4 ,  FIG. 6  illustrates a perspective view of a bottom of  FIG. 4 ,  FIG. 7  illustrates a perspective view of the stator in  FIG. 2 ,  FIG. 8  illustrates a perspective view of the connector in  FIG. 2 , and  FIG. 9  illustrates a perspective view of a bottom of  FIG. 8 . 
     Referring to  FIGS. 2A and 2B , the drum type washing machine in accordance with a first preferred embodiment of the present invention includes a tub  2  of a metal inside of a cabinet (not shown) for storage of water, a drum  3  inside of the tub  2 , a shaft  4  connected to the drum  3  for transmission of a driving force from a motor  5  to the drum  3 , a front bearing  6 a and a rear bearing  6 b respectively fitted to outer circumferences of both ends of the shaft  4 , a bearing housing  7  mounted to a rear wall  200  of the tub  2  for supporting the front and rear bearings, a rotor  13  mounted to a rear end of the shaft  4  to form a motor  5  together with a stator, the stator  14  on an inner side of the rotor  13  mounted to a rear wall  200  of the tub to form the motor together with the rotor, and a connector  16  serration coupled to the shaft  4  at a rear side of the rear bearing  6 b and fastened to the rotor  13  for transmission of a rotating force from the rotor to the shaft  4 . The bearing housing  7  is formed of a metal, preferably aluminum alloy. There is a hub  700  formed as one unit with the bearing housing  7  at a center thereof for fitting the front and rear bearings therein, and fastening bosses  701  formed on an outer side of the hub  700  at fixed intervals along a circumference for fastening the stator  14  to the bearing housing  7  with fastening members  15 d such that the bearing housing  7  looks like a semipalmate tripod in overall as shown in  FIG. 3 . A circular reinforcing rib 1005 connects the stator fastening bosses 701, as shown in FIG. 3. In this instance, there is a step  8 a and  8 b formed in an inside circumference of the hub  700  on a central portion of the bearing housing  7  at each end of the hub  700  for supporting the front bearing  6 a and the rear bearing  6 b so that respective bearings do not fall off, but are held therein. The step  8 a in the front has a form of “┐” for holding a rear end of the front bearing  6 a, and the step  8 b in the rear has a form of “└” for holding a front end of the rear bearing  6 b. And, there are positioning steps  9 a and  9 b at front and rear circumferences of the shaft  4  for positioning the front bearing  6 a and the rear bearing  6 b on the shaft  4 , respectively. The shaft  4  has a fore end held in a spider  10  in the rear wall of the drum  3 , an exposed portion from a rear end of the spider  10  to the front bearing  6 a having a bushing  11  of brass press fit thereon for prevention of rusting, with a sealing member  12  fitted on an outer circumference thereof for prevention of ingress of water, and a rear end having the rotor  13  of a direct coupling type motor  5  mounted on a center thereof. In this instance, a crown formed stator  14  is positioned on an inner side of the rotor  13 , fastened to the fastening bosses  701  on the bearing housing  7  to form the direct coupling type motor in combination with the rotor  13 . 
     In the meantime, referring to  FIGS. 4 to 6 , the rotor  13 , formed of a magnetic material, such as iron or iron alloy, has a rear wall  13 a, a side wall  13 b, and permanent magnets  13 c provided on the side wall. The side wall  13 b, extending from a periphery of the rear wall  13 a and serving as a back yoke that forms a magnetic flux path comprises a magnet setting surface  130 , a bent portion formed along a circumference thereof for supporting magnets  13 c fitted to an inside surface thereof and for reinforcing the rotor  13 . And, there is a hub  132  at a center of the rear wall  13 a having a through hole  131  for passing of a fastening member  15 a for preventing fall off of the shaft  4  from the connector  16  fixed to the rotor  13  from the shaft  4 . The rotor  13  is preferably formed by pressing. That is, the rotor  13  is formed by pressing as a unit both with the side wall  13 b having the magnet setting surface and the rear wall  13 a serving as a frame for supporting the side wall, without any separate additional fabrication process. 
     In general, the drum washing machine may cause a problem of temperature rise owing to a load since the drum and laundry should be run fast together. Therefore, there are a plurality of cooling fins around the hub  132  of the rotor  13  as a unit with the rotor  13  in a radial direction for blowing air toward the stator  14  in rotation of the rotor  13  to cool down a heat generated at the stator  14 . Each of the cooling fins  133  has a length in the radial direction. The cooling fin  133  is formed by lancing, to be bent at approx. 90° from the rear wall  13 a to direct toward opening, to form an opening  134  which serves as a vent hole. Accordingly, formation of the cooling fin  133  and formation of the vent hole are done by one process, different from a case when the formation of the vent hole is done by punching, thereby permitting saving in material and working hours as no separate component and process for forming the cooling fin is required. 
     And, different from BLDC motors used in VCR(Video Cassette Recorder) and the like, since the BLDC motor employed in the washing machine runs fast under a great load, a shape of the rotor is liable to deform during rotation of the rotor, which causes a non-uniform gap between the rotor and the stator. In order to eliminate this problem, there is an embossing  135  between every adjacent cooling fins  133  for reinforcing the rotor  13  together with the foregoing setting surface  130 . Moreover, there is a channel sectioned rim  13 d at an end of the rotor for stiffening the end for maintaining a true circle even if the rotor  13  rotates at a high speed. And, there is a draining hole  136  in the embossing  135  for discharge of water. And, there are fastening holes  137  for fastening the connector  16  serration coupled to an outer circumference of the shaft  4  at a rear end thereof exposed at a rear of the rear bearing  6 b and the positioning holes  138  for fixing a position of assembly of the connector  16 , both of which are formed around the through hole  131  in the hub  132  of the rotor  13  at fixed intervals. The connector  16  is formed of a resin which has a vibration mode different from the body of the rotor  13  of iron or iron alloy, for attenuating a vibration occurred in rotation of the drum. The fastening hole  137  and the positioning hole  138  in the connector  16  have diameters different from each other. 
     Referring to FIGS.  2 , 8  and  9 , the connector  16  has fastening holes  162  in correspondence to the fastening holes in the hub  132  of the rotor  13  along a circumference of a periphery thereof, and positioning projections between adjacent fastening holes  162  for automatic match between the fastening holes  137  in the rotor  13  and the fastening holes  162  in the connector  16  as the positioning projections  160  are inserted into the positioning holes  138  in the connector  13 . And, there is serration  164  in an inside circumference of the hub  163  of the connector  16  matched to the serration  400  in the rear end of the shaft  4 , and there are reinforcing ribs  161  on an outer side of the hub  163  of the connector  16  for reinforcing the hub  163 . 
     Referring to  FIGS. 2 and 7 , the stator  14 , forming the motor  5  together with the rotor  13 , includes a plurality of magnetic cores  145  formed by stacking magnetic laminations and each having a salient pole  141  projected outward in a radial direction, coils  142  wound around the salient poles  141 , a frame  140  of insulating material for covering top and bottom surfaces of a magnetic core assembly of the magnetic cores  145 , and fastening ribs  143  with fastening holes  143 a for fixing the stator  14  to the bearing housing  7 , the fastening ribs  143  formed as one unit with the frame  140  and projected inward in a radial direction. 
     There are tub brackets  17  welded to an outer circumference of the tub  2  for fixing the bearing housing  7  at a rear portion of the tub, and fastening holes  170  at rear ends of the tub brackets  17  for passing of fastening members  15 d fastened to the fastening holes  702  formed in an end portion of the bearing housing  7  in a radial direction. 
     The operation of the aforementioned structure of a driving unit in a drum type washing machine in accordance with a first preferred embodiment of the present invention will be explained. 
     Upon rotation of the rotor  13  as a current flows to the coils  142  of the stator  14  in a sequence under the control of a motor driving controller in a panel part(not shown), the shaft  4  serration coupled to the connector  16  which is in turn connected to the rotor is rotated, to rotate the drum  3  as a power is transmitted to the drum through the shaft  4 . 
     The assembly process of the first embodiment structure of a driving unit in a drum type washing machine of the present invention will be explained. 
     First, the drum  3  is placed inside of the tub  2 . In this instance, the bushing  11  is press fit on an exposed portion of the shaft from rear of the spider  10  to the front bearing  6 a for prevention of rusting of the shaft, and the sealing member  12  is fitted on the bushing  11  for prevention of ingress of water toward the bearing. Then, the front bearing  6 a is inserted on the shaft  4  in a state the drum  3  is placed inside of the tub  2 . After insertion of the front bearing  6 a, the bearing housing  7  is fixed to the rear of the tub as the fastening member  15 d passes through the fastening hole  170  in the tub bracket  17  welded to outer circumference of the tub  2  and fastened to the fastening hole  702  in the bearing housing  7 . After completion of mounting of the bearing housing  7  to the tub  2 , the rear bearing  6 b is fitted to the rear end of the shaft  4 . In this instance, the rear bearing  6 b is held at the step  9 b in rear portion of the shaft  4  and the step  8 b inside of the bearing housing  7  at an end thereof. In this condition, after the fastening holes  143 a in the fastening ribs  143  of the stator are aligned with the fastening bosses  701  on the bearing housing  7  on the outer side of the hub  700  at fixed intervals along a circumference, the stator is fastened to the fastening bosses  701  with the fastening members  15 c, to fix the stator  14  to the bearing housing  7 , firmly. Then, after an assembly of the rotor  13  and the connector  16 , which assembly is done separately, is inserted onto the rear end of the shaft  4 , the fastening member  15 a is fastened, to prevent the connector  16  from falling off the shaft by a fastening force of the fastening member  15 a. 
     The assembly process of the rotor  13  and the connector  16  will be explained. 
     First, the positioning holes  138  in the rotor  13  and the positioning projections  160  on the connector  16  are aligned, and the positioning projections  160  on the connector  16  are inserted into the positioning holes  138  in the rotor  13 . In this temporary assembly when the positioning projections  160  on the connector  16  are merely inserted into the positioning holes  138  in the rotor  13 , the fastening holes  137  in the rotor  13  and the fastening holes  162  in the connector  16  are aligned, under which condition, the fastening members  15 b are fastened through the fastening holes  137  and  162 , to assemble the rotor  13  and the connector  16  together. 
     The operation of the structure of a driving unit in a drum type washing machine of the first preferred embodiment of the present invention assembled thus will be explained. 
     The bearing housing  7  of a metal, such as aluminum alloy, is applicable to the drum type washing machine which has a drying cycle since the bearing housing  7  shows no thermal deformation even at a high temperature. The “┐” formed step  8 a in the front, and the “└” formed step  8 b in the rear of the inside circumference of the bearing housing  7  hold a rear end of the front bearing  6 a and a front end of the rear bearing  6 b fitted on outer circumferences of the shaft  4  at both ends thereof, respectively. The positioning steps  9 a and  9 b in outer circumferences of a front portion and a rear portion of the shaft  4  permit to fix positions of the front bearing  6 a and the rear bearing  6 b with respect to the shaft  4 . In the meantime, the front end of the shaft  4  is fixed in the spider  10  mounted to a rear wall of the drum  3 , the exposed portion of the shaft from rear of the spider  10  to the front bearing  6 a has the bushing  11  press fit thereon for prevention of rusting of the shaft, and the sealing member  12  is fitted on the bushing  11  for prevention of ingress of water toward the bearing. The fastening bosses  701  on the bearing housing  7  on the outer side of the hub  700  at fixed intervals along a circumference permits the stator  14  to be fastened to the fastening bosses  701  with the fastening members  15 c, to fix the stator  14  to the bearing housing  7 , firmly. And, the rotor  13  of the direct coupling type motor  5  is fixed to the rear end of the shaft  4 , and the bent part having the magnet setting surface  30  formed along a circumference of the sidewall  13 b extended forward from a periphery of the rear wall  13 a of the rotor  13  supports the magnets  13 c attached to the rotor  13 , thereby permitting an easy fabrication of the rotor. The through hole  131  in the hub  132  at a center of the rear wall  13 a of the rotor  13  permits to fasten the fastening members  15 a, such as bolts, to the rear end of the shaft for prevention of falling of the shaft  4  off the rotor  13  and the connector  16  coupled to the rotor  13 , and the plurality of cooling fins  133  formed around the hub  132  of the rotor  13  in a radial direction each with a length blow air toward the stator  14  when the rotor  13  is rotated, thereby cooling down the heat generated at the stator  14 . The cooling fin  133  formed to direct the open side of the rotor  13  by lancing forms the through hole  134  which serves as a vent hole. The body of the rotor  13  formed of iron or iron alloy by pressing reduces a fabrication time period very much, to improve a productivity of the rotor. The embossing  135  between adjacent cooling fins  133  on the rear wall  13 a of the rotor improve an overall strength of the rotor  13 , and the draining hole  136  in the embossing  135  permits to discharge water. The fastening holes  137  for fastening the connector and the positioning holes  138  for fixing a position of assembly of the connector  16 , both of which are formed around the through hole  131  in the hub  132  of the rotor  13  permits to assemble the connector  16 , serration coupled to the rear end of the shaft  4  exposed in rear of the rear bearing  6 b, and the rotor  13  with easy. Once the positioning projections on the connector  16  are aligned with the positioning holes  138  in the rotor  13 , the fastening holes  137  and  162  in both of the rotor  13  and the connector  16  are aligned automatically, through which the fastening members  15 b are fastened, to assemble the connector  16  and the rotor  13  with easy. In this instance, the connector  16  of a resin injection molding has a vibration mode different from the same of the rotor  13  of iron or iron alloy, to attenuate the vibration from the rotor  13  to the shaft  4 . The serration  164  on an inside circumference of the hub  163  of the connector  16  is fitted to the serration  400  on the rear end of the shaft  4 , to transmit a rotation force from the rotor  13  to the shaft  4  as it is. There is a cylindrical outer rib  165  spaced from the outer circumference of the hub  163 , an end of which is brought into close contact with the rotor for being held, firmly. A space  166  formed between the hub  163  and the outer rib  165  cuts off transmission of vibration from the shaft to the rotor or vice versa. The reinforcing ribs  161  in the space  166  connecting the hub  163  and the outer ribs  167  permits an overall strength of the connector  16  to be adequate. 
     A structure of 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 to  FIGS. 10 and 11 .  FIG. 10  illustrates a longitudinal section of key parts of a structure of a driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention, and  FIG. 11  illustrates a right side view of  FIG. 10  having a motor removed therefrom. Second embodiment components identical to the first embodiment will be given the same reference symbols, and explanations of which will be omitted. The second embodiment structure of a driving unit in a drum type washing machine of the present invention further includes an a skirt or arc formed baffle  703  on an upper portion of outer side of the rotor  13  mounted to the bearing housing  7  for prevention of ingress of water into a motor  5 , which water is dropped from a water supply valve  27  when the water supply valve  27  is out of order. The arc formed baffle  703  has a length connecting both ends of the arc greater than a diameter of the rotor  13 . Provided that the baffle  703  is formed to have a length enough to project an end thereof beyond a rear of the sidewall  13 b of the rotor, though it does not matter that an angle θ between the rear wall  200  of the tub and a top surface of the baffle  703  is 90° or greater than 90°, it is preferable that the angle θ μs smaller than 90°. 
     The operation of the aforementioned structure of a driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention will be explained. 
     In the related art, since the motor  5 a is mounted to a lower portion of the tub  2 , chances are low that water will invade into the motor  5 a even if water drops leak from the water supply valve  25 . But in a drum type washing machine with the structure of a driving unit of the present invention, since the motor  5  is mounted to a rear of the tub  2 , if the water supply valve  27  gets out of order and water leaks, the leaking water is liable to fall toward the motor  5  an invade into it, which should be prevented. In order to prevent this in the present invention, the arc formed baffle  703  is provided to surround the rotor from an outer upper side of the rotor in the bearing housing  7  for prevention of the water flow toward the motor  5 , thereby securing a reliability of the motor without shifting a position of the water supply valve  27 . It is preferable that the angle θ between the rear wall  200  of the tub  2  and the top surface of the baffle  703  is less than 90° so that the water flows on the rear wall, but the angle θ does not matter as far as a length of the baffle  703  from a fixed end to a free end is enough to cover the sidewall  13 b of the rotor. 
     A structure of a driving unit in a drum type washing machine in accordance with a third preferred embodiment of the present invention will be explained with reference to  FIG. 12 .  FIG. 12  illustrates a longitudinal section of key parts of a structure of a driving unit in a drum type washing machine in accordance with a third preferred embodiment of the present invention. Third embodiment components identical to the first or second embodiment will be given the same reference symbols, and explanations of which will be omitted. 
     Referring to  FIG. 12 , the structure of a driving unit in a drum type washing machine in accordance with a third preferred embodiment of the present invention further includes a ring-shaped, self aligning type rib  705  having a slope  705 a at one side thereof formed in the bearing housing  7  along a circumference on an outer side of the fastening boss  701 , and a ring-shaped, self aligning type rib  144  having a slope  144 a in correspondence to the slope  705 a in the self aligning type rib  705  on an inner side of a frame  140  of the stator  14 . 
     The operation of the aforementioned structure of a driving unit in a drum type washing machine in accordance with a third preferred embodiment of the present invention will be explained. 
     The self aligning type rib  705  having a slope  705 a at one side thereof formed in the bearing housing  7  along a circumference on an outer side of the fastening boss  701 , and the self aligning type rib  144  having a slope  144 a in correspondence to the slope  705 a in the self aligning type rib  705  on an inner side of a frame  140  of the stator  14  permits self alignment of the stator  14  with the hub  700  on the bearing housing  7  on an exact concentric circles in assembly, thereby permitting an easy assembly of the stator to the bearing housing. 
     A structure of a driving unit in a drum type washing machine in accordance with a fourth preferred embodiment of the present invention will be explained with reference to  FIG. 13 .  FIG. 13  illustrates a longitudinal section of key parts of a structure of a driving unit in a drum type washing machine in accordance with a second preferred embodiment of the present invention. 
     Referring to FIG  13 , the structure of a driving unit in a drum type washing machine in accordance with a fourth preferred embodiment of the present invention includes a tub  2  having a hub  201  projected forward from a central portion of a rear wall  200  inside of a cabinet(not shown) for storage of water, a drum  3  inside of the tub  2 , a shaft  4  connected to the drum  3  for transmission of a driving force from a motor  5  to the drum  3 , a front bearing  6 a and a rear bearing  6 b respectively fitted to outer circumferences of both ends of the shaft  4 , a supporting bracket  8  fastened to one side of the hub  201  of the tub  2  by fastening members  15 d passed through fastening holes  801  having a step  800  for supporting the rear bearing  6 b and fastening holes  802  for mounting the stator thereon, a connector  16  serration coupled to a rear end of the shaft  4 , a rotor  13  of the motor  5  together with the stator coupled to the connector  16 , and the stator  14  of the motor together with the rotor  13  fastened to the rear wall  200  of the tub on an inner side of the rotor  13 . The bracket  8  is preferably formed of a metal, such as an aluminum alloy. There is a step  202  at an inside end of the hub  201  of the tub  2  for holding a front end of the front bearing  6 a fitted on an outer circumference of the shaft  4  at a front end thereof. And, the step  800  at an inside end of the supporting bracket  8  holds a front end of the rear bearing  6 b fitted on an outer circumference of the shaft  4  at a rear end thereof. In the meantime, the shaft  4  inside of the supporting bracket  8  for transmission of a driving force from the motor  5  has positioning steps  9 a and  9 b in an outer circumferences of a front end and a rear end thereof for fixing positions of the front bearing  6 a and the rear bearing  6 b with respect to the shaft  4 , a front end fixed to a spider  10  provided to the rear wall of the drum  3 , an exposed portion from a rear end of the spider  10  to the front bearing  6 a having a bushing  11  of brass press fit thereon for prevention of rusting, with a sealing member  12  fitted on an outer circumference thereof for prevention of ingress of water, and a rear end having a fastening member  15 a fastened to a center for preventing the connector for connection with the rotor  13  of the direct coupling type motor  5  from falling off. The stator  14  of the direct coupling type motor is positioned on an inner side of the rotor  13  and fastened to the fastening holes  801  in the supporting bracket  8 . And, there is a arc formed baffle  210  on an upper portion of the rear wall of the tub  2  for prevention of water flow into the motor  5  dropped from the water supply valve when the water supply valve  25  is out of order. The arc formed baffle  210  has a length connecting both ends of the baffle greater than a diameter of the rotor. Provided that the baffle  210  is formed to have a length enough to project an end thereof beyond a rear of the sidewall  13 b of the rotor, though it does not matter that an angle θ between the rear wall  200  of the tub and a top surface of the baffle  210  is 90° or greater than 90°, it is preferable that the angle θ is smaller than 90°. 
     Since the rotor, stator, connector, and the baffle have structures identical to the first and second embodiments, explanations of which will be omitted. 
     The operation of the structure of a driving unit in a drum type washing machine in accordance with a fourth preferred embodiment of the present invention will be explained. 
     When the rotor  13  is related as a current flows to the coils  142  of the stator  14  in a sequence under the control of a motor driving controller on a panel part(not shown), the shaft  4 , serration coupled to the connector  16  which is in turn connected to the rotor, is rotated, to rotate the drum  3  as a power is transmitted to the drum through the shaft  4 . 
     The assembly process of the fourth embodiment structure of a driving unit in a drum type washing machine of the present invention will be explained. 
     First, the front bearing  6 a is inserted onto the shaft  4  in a condition the drum  3  having the shaft  4  fixed to the spider  10  at a rear of the drum  3  is assembled inside of the tub  1 . According to this, the from beating  6 a inserted onto the outer circumference of the shaft  4  is fixed at the front bearing  6 a is held both at the step  9 a in a front portion of the shaft  4  and the step  202  in the hub  200  of the tub  2 . Then, under a condition that the fastening holes  203  for fastening the supporting bracket formed in the hub  201  of the tub  2  and the fastening holes  801  in the supporting bracket  8  are aligned, the fastening members  15 d are fastened, to fix the supporting bracket  8  to the hub  201  of the tub  2 . After assembly of the supporting bracket  8  to the tub  2 , the rear bearing  6 b is inserted onto the shaft  4  through the rear end of the shaft  4  until the rear bearing  6 b is held both at the step  9 b in a rear portion of the shaft  4  and the step  800  in an inside end of the supporting bracket  8 . Then, the fastening holes  802  in the periphery of the supporting bracket  8  and the fastening holes  143 a in the fastening rib  143  of the stator  14  are aligned, and fastened with the fastening members  15 c. Under this condition, an assembly of the rotor  13  and the connector  16  are inserted into the rear end of the shaft  4 , and the fastening member  15 a is screwed into the rear end of the shaft, for preventing the connector  16  from falling off the shaft by a fastening force of the fastening member  15 a, thereby fixing the stator  14  to the supporting bracket  8 . 
     The operation of the structure of a driving unit in a drum type washing machine in accordance with a fourth preferred embodiment of the present invention will be explained. 
     In the fourth embodiment structure of a driving unit in a drum type washing machine of the present invention, since the supporting bracket  8  is formed of a metal, such as aluminum alloy, which is involved in no thermal deformation even at a high temperature, the supporting bracket  8  is applicable to the drum type washing machine which has a drying cycle. That is, the step  800  in an inside end of the supporting bracket  8  in the fourth preferred embodiment of the present invention permits to support the front end of the rear bearing  6 b. And, the positioning steps  9 a and  9 b in outer circumferences of front and rear portions of the shaft  4  disposed inside of the supporting bracket  8  for transmission of a driving force from the motor  5  to the drum  3  permit easy positioning of the front and rear bearings  6 a and  6 b with respect to the shaft  4 . In the meantime, the front end of the shaft  4  is fixed to the spider  10  in the rear wall of the drum  3 , and a portion of the shaft  4  from an end of the spider  10  to the front bearing  6 a has a bushing  11  of brass press fit thereon, for prevention of rusting of the shaft  4 . And, the sealing member  12  on an outer circumference of the bushing  11  prevents ingress of water into the bearing. The fastening holes  802  in the periphery of the supporting bracket  8  at fixed intervals along a circumference permit the fastening members  15 c passed through the fastening holes  143 a in the fastening ribs  143  on the stator  14  to pass through the fastening holes  802  in the supporting bracket, thereby permitting the stator  14  fixed to the supporting bracket  8 , firmly. As the serration  164  on the inside circumference of the hub  201  of the connector  16  is fitted to the serration  400  on the rear end of the shaft  4 , a rotation force can be transmitted from the rotor  13  to the shaft  4  through the connector  16  as it is. Since the supporting bracket  8  is fastened to the hub  201  projected forward from a central portion of the rear wall  200  of the tub in a face to face contact, and the stator  14  is fixed to the supporting bracket  8 , a distance from the rear wall  200  of the tub to the stator  14  is very close, which permits to minimize a distance from the rear wall  200  of the tub to the rear wall  13 a of the rotor, that permits to provide a compact product. 
     As has been explained, the structure of a driving unit in a drum type washing machine of the present invention has the following advantages. 
     The first to third embodiment structure of a driving unit in a drum type washing machine can reduce noise, trouble caused by being out of order, and power loss as it is of a motor direct coupling type. 
     And, the first to third embodiment structure of a driving unit in a drum type washing machine can be applicable to a product with a drying function as the drum type washing machine of the present invention has a bearing housing formed of a metal. 
     And, the first to third embodiment structure of a driving unit in a drum type washing machine can improve a productivity because the rotor of iron or iron alloy in the drum type washing machine of the present invention is fabricated by pressing, which has a good formability and a short fabrication time period. 
     And, the first to third embodiment structure of a driving unit in a drum type washing machine can improve workability in fitting magnets as the rotor has a magnet setting surface, and can prevent over heating of the motor as the rotor has draining holes, cooling fins and vent holes to improve a reliability and a lifetime of the motor. 
     And, the second embodiment structure of a driving unit in a drum type washing machine can prevent ingress of water dropped from the water supply valve  27  into the motor by means of the arc formed baffle on an upper portion of the bearing housing, thereby assuring a motor reliability. 
     And, the third embodiment structure of a driving unit in a drum type washing machine permits assembly of the stator with easy when the stator is mounted to the rear of the bearing housing owing to the self alignment action of the ribs. 
     And, the fourth embodiment structure of a driving unit in a drum type washing machine can also reduce noise, trouble from being out of order, and a power loss as it is of the motor direct coupling type. 
     And, the fourth embodiment structure of a driving unit in a drum type washing machine can be applied to a product with a dry function as the supporting bracket of a metal shows no thermal deformation. 
     And, the fourth embodiment structure of a driving unit in a drum type washing machine can prevent ingress of water dropped from the water supply valve into the motor  5  by means of the arc formed baffle provided at a rear of the tub, thereby assuring a reliability of the motor. 
     Thus, since the drum type washing machine of the present invention can improve a structure of a driving unit, to permit direct transmission of a driving force from the motor to the drum directly, noise and trouble as well as a power loss can be reduced, to improve a productivity of the rotor and the product. 
     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.