Abstract:
A washing machine with a balancer is provided which is capable of improving the balancing capacity of the balancer with respect to conventional devices, preventing the balancer from being damaged due to thermal expansion, and simplifying the manufacture and assembly of the balancer. The washing machine includes an outer tab for accommodating washing water. An inner tub is rotatably mounted in the outer tab for washing and spin-drying the laundry. A balancer is mounted to the inner tub to be opened at one side. The balancer accommodates water to balance the inner tub. Water supply means supplies washing water to the balancer. A cabinet encloses the components of the washing machine.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a washing machine with a balancer, and more particularly to a washing machine, which is equipped with a balancer on a portion of the inner tub of the washing machine having a horizontally disposed drive shaft, thereby reducing its vibration and noise during a spin-drying process. 
     2. Description of the Prior Art 
     As shown in FIG. 1, a conventional washing machine includes a cabinet  1 . A door  3  is openably mounted to the front of the cabinet  1  to allow the laundry to be fed and discharged. An outer tub  5  is situated in the cabinet  1  to accommodate water. 
     An inner tub  7  provided with a plurality of water passage holes  7   a  is rotatably positioned in the outer tub  5 . A lifter  9  is mounted on the bottom of the interior of the inner tub  7  to raise the washing water to a predetermined height and, thereafter, allow it to fall down due to gravitational force. A water supply hose  13  passes through the cabinet  1 , and a water supply valve  11  is positioned on the water supply hose  13 , so as to supply water necessary for washing. A detergent container  15  is formed in the upper portion of the cabinet  1  to supply a detergent. A water supply bellows  17  is situated between the detergent container  15  and the outer tub  5  to supply to the outer tub  5  water that has been supplied through the water supply hose  13  and has been mixed with the detergent. 
     A motor  19  is mounted beneath the outer tub  5 . A belt  21  and a pulley  23  are situated in the vicinity of the motor  19  to rotate the inner tub  7  normally and reversely. 
     A water drain bellows  25  is situated under the outer tub  5  to drain water that is used in the washing machine. A drain pump  27  is mounted to the end portion of the drain bellows  25  to pump water that is drained through the water drain bellows  25 . A drain hose  29  is connected to the drain pump  27  to drain to the outside water pumped by the drain pump  27 . 
     A water level sensor  31  is positioned in the cabinet  1  so as to sense a water level by means of water pressure to determine if water is supplied to the outer tub  5  or not. A gasket  35  is interposed between the door  3  and the outer tub  5  to prevent water contained in the outer tub  5  from leaking. 
     Reference numerals  37 ,  39  and  25   a  designate a spring for supporting the upper portion of the outer tub  5 , a damper for supporting the lower portion of the outer tub  5  and reducing the vibrations of the outer tub  5 , and a drain valve, respectively. 
     However, in the conventional drum washing machine, there occurs a shortcoming in which the inner tub  7  is imbalanced due to the maldistribution of the laundry when the inner tub  7  is rotated at a high speed to spin-dry the laundry, thereby generating vibration and noise. 
     In the meantime, in the conventional vertical washing machine (in which a drive shaft is positioned perpendicular to the ground), there occur shortcomings in which the balancing force of the balancer cannot be adjusted due to its balancer being hermetically sealed, its balancer may be damaged due to its thermal expansion during the heating of washing water and, the manufacture and assembly of its balancer is difficult. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a washing machine with a balancer, which is capable of improving the balancing capacity of its balancer to reduce vibration and noise, of preventing the balancer from being damaged due to thermal expansion to increase the durability of the balancer, and of simplifying the manufacture and assembly of the balancer to reduce the manufacturing cost of the washing machine. 
     In order to accomplish the above object, the present invention provides a washing machine, comprising an outer tub for accommodating washing water, an inner tub rotatably mounted in the outer tub for washing and spin-drying the laundry, a balancer mounted to the inner tub to be opened at its one side, the balancer accommodating water to balance the inner tub, water supply means for supplying washing water to the balancer, and a cabinet for constituting the boundary of the washing machine and enclosing the components of the washing machine. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a vertical cross section of a conventional washing machine; 
     FIG. 2 is a vertical cross section of a washing machine in accordance with the preferred embodiment of the present invention; 
     FIG. 3 is enlarged view of “A” portion of FIG. 2; 
     FIG. 4 is an enlarged, exploded perspective view showing the principal components of the washing machine; 
     FIG. 5 is a cross section of a balancer in accordance with the preferred embodiment of the present invention; and 
     FIG. 6 is a graph in which the displacements of an inner tub are plotted with regard to the rotational speeds of an inner tub. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. 
     With reference to FIGS. 2 to  6 , there is described a preferred embodiment of the present invention. 
     FIG. 2 is a vertical cross section of a washing machine in accordance with the preferred embodiment of the present invention. FIG. 3 is enlarged view of “A” portion of FIG.  2 . FIG. 4 is an enlarged, exploded perspective view showing the principal components of the washing machine. FIG. 5 is a cross section of a balancer in accordance with the preferred embodiment of the present invention. FIG. 6 is a graph in which the displacements of an inner tub are plotted with regard to the rotational speeds of an inner tub. 
     As shown in FIG. 2, the washing machine of the present invention includes a cabinet  1  that constitutes the boundary of the washing machine. A door  3  is openably mounted to the front of the cabinet  1  to allow the laundry to be fed and discharged. An outer tub  5  is situated in the cabinet  1  to accommodate washing water. An inner tub  7  provided with a plurality of water passage holes  7   a  is rotatably positioned in the outer tub  5 . A lifter  9  is mounted on the bottom of the interior of the inner tub  7 . A water supply means is mounted to the interior of the cabinet  1  to supply washing water to the washing machine. A motor  19  is attached beneath the outer tub  5 . A belt  21  and a pulley  23  are situated in the vicinity of the motor  19  to rotate the inner tub  7  normally and reversely. 
     A balancer  100  is mounted to the front end of the inner tub  7  to balance the inner tub  7  during high-speed rotation for a spin-drying process, thereby reducing vibration and noise. The balancer  100  may be attached to the front end of the inner tub  7  in a tight-fitting or welding fashion, or may be integrally formed with the inner tub  7 . 
     The balancer  100  comprises a cylindrical portion  101  extended horizontally, a bell portion  102  expanded downwardly rearward from the rear end of the cylindrical portion  101 , a skirt portion  103  extended from the rear end of the bell portion  102  to the rear end of the cylindrical portion  101 , and a bent portion  104  extended radially inward from the front end of the skirt portion  103  to be spaced apart from the cylindrical portion  101  and form an opening  105  between the cylindrical portion  101  and itself. Accordingly, a space is formed between the bell portion  102 , the skirt portion  103  and the bent portion  104  to accommodate water, and the cylindrical portion  101  is projected forward past the bent portion  104 . 
     As a result, as the balancer  100  is rotated, water having being supplied to the space  106  through the opening  105  is moved through the skirt portion  103  and fills the entire space  106 , due to centrifugal force. 
     A speed sensor  210  is mounted to a portion of the motor  19  to sense that the rotational speed of the inner tub  7  passes through a critical speed (see “C” in FIG. 6) of the inner tub  7  and reaches a speed (see “B” in FIG. 6) at which the centrifugal force exceeds gravitational force. The water supply means is comprised of a water supply source  200 , a water supply hose  230  for supplying water from the water supply source  200  to the space  106  of the balancer  100  through the opening  105  of the balancer  100 , and a water supply valve  220  mounted on the water supply hose  230  for selectively being opened and closed in response to a signal from the speed sensor  210 . 
     The critical speed denotes a speed in which the amplitude of vibration is infinitely enlarged due to the coincidence of the natural frequency of the inner tub and the rotational speed of a drive shaft during the rotation of the drive shaft along with the inner tub  7 . 
     Next there is described the operation of the washing machine with a balancer. 
     When a user starts the washing machine by manipulating a control panel (not shown) after opening the door  7 , feeding the laundry into the inner tub  7  and shutting the door  7 , the water supply valve  220  is turned ON, and water is initially supplied through the water supply hose  230  and sent to the space  106  of the balancer  100  through the opening  105  of the balancer  100 . At this time, water having filled the space of the balancer  100  overflows through the opening  105  of the balancer  100  into the outer tub  5 , and thereafter water having overflowed into the outer tub  5  passes through the water passage holes  7   a  and fills the inner tub  7 . 
     When water fills the outer and inner tubs  5  and  7  to a predetermined height, the water pressure of the interior of the outer tub  5  is transmitted to the water level sensor  31  through the drain bellows  25  and a water level sensor hose  33 . As a result, the water supply valve  220  is turned OFF, thereby stopping a water supply process. 
     When the water supply is stopped, washing and rinsing processes are performed while the motor  19  is operated and the inner tub  7  is normally and reversely rotated by means of the belt  21  and the pulley  23 . 
     At this time, the laundry is raised up to a predetermined height by means of the lifter  9  and lowered down from the height by means of gravitational force, so that the laundry is washed through a mechanical operation. 
     After the washing and rinsing processes are performed, the drain valve  25   a  is opened, washing water is drained through the drain bellows  25 , and the washing water having passed through the drain bellows  25  is pumped by the drain pump  27  and drained to the outside through the drain hose  29 . 
     Meanwhile, after the washing and rinsing processes are performed, the motor  19  is rotated in a predetermined direction to spin-dry the laundry and the inner tub  7  is also rotated in the direction, so that the laundry is spin-dried by means of centrifugal force. Water removed from the laundry is drained to the outside through the water passage holes  7   a  of the inner tub  7 , the outer tub  5 , the drain bellows  25 , the drain pump  27  and the drain hose  29 . 
     When the speed sensor  210  mounted to a portion of the motor  19  senses that the rotational speed of the inner tub  7  passes through the critical speed of the inner tub  7  and reaches a speed at which the centrifugal force exceeds gravitational force, the water supply valve  220  is opened and water is supplied from the water supply source  200  through the water supply hose  230 . Water having been supplied through the water supply hose  230  is supplied to the space  106  through the opening  105  of the balancer  100 . 
     The water having entered the space  106  balances the inner tub  7  tending to lean while being brought into tight contact with and flowing along the inner surface of the skirt portion  103  of the balancer  100  by means of centrifugal force, thereby reducing vibration and noise. 
     The balancing capacity of the balancer  100  depends upon the amount of water supplied to the space  106  and the height H of the bent portion  104 . 
     In the meantime, in the case of utilizing boiled water, the balancer  100  is not damaged due to thermal expansion because the balancer  100  can absorb the effect of the thermal expansion due to the presence of the opening  105 . 
     Although the speed sensor  210  is described as being mounted to a portion of the motor  19 , the position of the speed sensor  210  is not limited to that position, but the speed sensor  210  may be mounted to a portion of the inner tub  7  to sense the rotational speed of the inner tub  7 . 
     In addition, although water is described as being supplied through the space  106  of the balancer  100 , the washing water can be supplied in other ways. That is, during washing and rinsing processes water may be supplied through a portion of the outer tub  5  as in a conventional art, while during a spin-drying process water may be supplied to the interior of the balancer  100 . 
     FIG. 6 is a graph in which the maximum displacements of the inner tub  7  with and without the balancer  100  are plotted with regard to the rotational speeds of the inner tub  7 . In the graph, an “X” axis represents the rotational speeds of the inner tub  7  during a spin-drying process, while a “Y” axis represents the maximum displacements of the inner tub  7 . The speed “B” denotes a speed that the inner tub  7  reaches after passing through the critical speed C and at which centrifugal force exceeds gravitational force. 
     In the graph, a dotted line represents the displacements of the inner tub  7  without the balancer  100  with regard to the maximum rotational speed of the inner tub  7  without the balancer  100 , while a solid line represents the displacements of the inner tub  7  with the balancer  100  with regard to the maximum rotational speed of the inner tub  7  with the balancer  100 . As apparent from the graph, in a case where the balancer  100  is mounted to the inner tub  7  the displacements of the inner tub  7  can be reduced. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.