Abstract:
A laundry treatment apparatus is provided to improve energy efficiency by generating steam by a steam generating means using ultrasonic waves and reduce production costs and improve working efficiency by reduction of the number of heat suppliers by heating the generated steam by a heat supplier provided at a dryer. The laundry treatment apparatus includes a cabinet; a washing tub disposed inside the cabinet to treat laundry put therein; and an ultrasonic steam generating means for generating steam to be supplied into the washing tub by using ultrasonic waves.

Description:
[0001]    This application claims priority from Korean Patent Application No. 10-2007-0100931, filed on Oct. 8, 2007 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a steam generating means which is used for a laundry treatment apparatus for treating laundry, such as a drum washing machine, a tower type washing machine, and a refresher. 
         [0004]    2. Discussion of the Related Art 
         [0005]    In general, a laundry treatment apparatus is commonly known as a washer which is an appliance for removing contaminants stuck to clothes, beddings and the like (hereinafter, referred to as “laundry”) by using a chemical decomposition of water and detergent and a physical action, such as friction between water and laundry and a refresher for washing laundry easily by jetting steam to the laundry. 
         [0006]    Such laundry treatment apparatuses are divided into a tower type washing machine for doing laundry by friction between laundry by forming turbulence in wash water in a washing tub that is raised and a drum type washing machine for washing laundry by a physical impact generated by the rotation of the drum when the laundry put into a drum is lifted by a lifter formed in the drum and then dropped. 
         [0007]    Recently, a laundry treatment apparatus having a steam generator for generating heated steam and applying the steam to laundry has been provided. Such a laundry treatment apparatus provides the function of easily washing laundry by jetting steam to the laundry, increases the solubility of a detergent by raising the temperature in the laundry and washing tub by adding a steam heating means, and makes contaminants stuck to the laundry swollen so that they can be easily removed during washing, thereby greatly improving washing performance. Thus, the demand thereof is increasing steadily. 
         [0008]    By the way, a conventional steam wash-type steam generator employs the method of generating steam by using the phenomenon that water boils by heating, so a lot of energy is consumed to raise the temperature of water. However, it is not always necessary for the temperature in the washing tub to reach a water boiling point to achieve positive effects such as a sufficient solubility of detergent and an increase in the swelling of dirt of the laundry. Further, considerable time is required to heat water until boiling, thus lengthening the washing time. 
         [0009]    Besides, since recent washing machines generally have a dryer for drying laundry, one heat supplier for use in a dryer and another heat supplier for use in a steam generator should be installed in the washing machine because a conventional steam generator employs the method of increasing the temperature of water for steam generation. This leads to the problem of an increase in the production cost of a washing machine. 
       SUMMARY OF THE INVENTION 
       [0010]    An object of the present invention is to provide a laundry treatment apparatus which can reduce fabrication costs by reducing components and improve energy efficiency by reducing energy consumption. 
         [0011]    To achieve the above object, there is provided a laundry treatment apparatus according to the present invention, comprising: a cabinet; a washing tub disposed inside the cabinet to treat laundry put therein; and an ultrasonic steam generating means for generating steam to be supplied into the washing tub by using ultrasonic waves. 
         [0012]    The laundry treatment apparatus may further comprise a steam heater for heating the steam generated by the ultrasonic steam generating means. 
         [0013]    Preferably, the laundry treatment apparatus may further comprise a dryer for drying air to be supplied into the washing tub, the dryer being adapted to heat the steam generated by the ultrasonic steam generating means. 
         [0014]    The dryer may further comprise a drying duct for inducing the flow of air and a heat supplier for supplying heat to the air passing through the drying duct to dry the air. 
         [0015]    Preferably, the steam generated by the ultrasonic generating means may be heated by receiving heat from the heat supplier while passing through the drying duct. 
         [0016]    Preferably, the dryer may further comprise a blower for sending the air dried by being passed through the heat supplier into the washing tub. 
         [0017]    First, washing time can be shortened by reducing the steam generation time. 
         [0018]    Second, the energy required for steam generation can be reduced because there is no need to heat water more than necessary for the generation of steam, and accordingly energy efficiency can be increased. 
         [0019]    Third, steam heating time can be shortened by heating the steam to be supplied into the washing tub. 
         [0020]    Fourth, costs can be reduced by a reduction of the number of heat suppliers because a heat supplier for heating steam can be shared with the dryer. 
         [0021]    Fifth, it is possible to simplify an assembling process and reduce costs by simplification of the apparatus by providing a steam generating means in the dryer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
           [0023]      FIG. 1  is a perspective view illustrating a drum washing machine in accordance with a first embodiment of the present invention; 
           [0024]      FIG. 2  is a cross sectional view taken along line II-II of  FIG. 1 ; 
           [0025]      FIG. 3  is a cross sectional view taken along line III-III of  FIG. 1 ; 
           [0026]      FIG. 4  is a cross sectional view of a steam generating means according to the present invention; and 
           [0027]      FIG. 5  is a cross sectional view of a dryer according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    Hereinafter, an embodiment of the present invention will be described by utilizing a drum washing machine as a primary apparatus. However, this is only for avoiding redundant description because the present invention is freely applicable regardless of the type of a laundry treatment apparatus. This invention can be commonly used for all laundry treatment apparatuses for treating laundry by means of steam, such as a tower type washing machine or a refresher for treating laundry by jetting steam. 
         [0029]    Hereinafter, the present invention will be described with reference to  FIGS. 1 to 5 . 
         [0030]    Hereinafter, a general view of a laundry treatment apparatus according to the present invention will be described with reference to  FIGS. 1 to 3 . 
         [0031]    A washing machine  1  includes a cabinet  2  forming the outer appearance of the washing machine  1 , a washing tub  40  installed in the cabinet  2  and performing washing of laundry, a driving source  5  mounted at the rear of the washing tub  40  and providing a driving force to be transmitted to the washing tub  40 , a cabinet cover  8  mounted on the front surface of the cabinet  2  and having a laundry entrance  8 A formed at the center, a door  10  rotatably installed on the cabinet cover  8  so as to open and close the laundry entrance  8 A of the cabinet cover  8 , a steam generating means  100  for supplying steam into the washing tub  40 , a dryer  200  for drying laundry by providing dried air into the washing tub  40 , and a detergent supplier  60  for supplying detergent into the washing tub  40  along with supplied water. 
         [0032]    Although  FIG. 3  illustrates the steam generating means  100  and the dryer  200  as being installed as separate devices, the present invention is not necessarily limited, but the steam generating means and the dryer may be provided and installed together within the same housing. 
         [0033]    The washing tub  40  may include a tub  30  installed in the cabinet  2  so as to be damped by springs  12 A and a damper  12 B and containing wash water, a drum  20  rotatably installed in the tub  30  by the driving source  5  to hold laundry and having a plurality of through holes  20 A through which wash water passes, and a lifter  22  installed on an inner surface of the drum  20  so that laundry can be lifted to a predetermined height and then dropped by gravity during the rotation of the drum  20 . 
         [0034]    Although the washing tub  40  has a structure having a drum and a tub because the present invention is described with respect to a drum washing machine, a washing tub of a laundry treatment apparatus of another type is not necessarily limited thereto. 
         [0035]    A water supply device  80  forming a water supply passage of the washing tub  40  or steam generating means  100  is installed on the upper side of the washing tub  40 . The water supply device  80  includes a water supply valve  82  installed in the cabinet  2  and controlling the flow of water introduced from the outside, and a water supply hose  84  whose one end is connected to the water supply valve  82  to guide water to the tub  30 , steam generating means  100 , and detergent supplier  60 . 
         [0036]    The steam generating means  100  is generally installed on an upper side in the cabinet so as to supply steam into the washing tub  40  in a steam washing or steam rinsing step. The steam generating means  40  is communicatively installed on the water supply passage formed between the water supply valve  82  and the washing tub  40 , so that water W to be changed into steam is supplied to the steam generating means from the water supply device  80  via a water supply hose  130  for steam generation and the water is transformed into steam by using ultrasonic waves. 
         [0037]    Hereinafter, the steam generating means  100  and dryer  200  of the present invention and a combination of them will be described concretely with reference to  FIGS. 4 and 5 . 
         [0038]    Referring to  FIG. 4 , the steam generating means in accordance with a preferred embodiment of the present invention will be described. The steam generating means  100  includes a first water tank  160  for receiving and storing water supplied from the water supply device  80 , a second water tank  170  which is a space for transforming the water supplied from the first water tank  160  into steam, a water level control valve  120  for controlling the water level of the second water tank  170  by adjusting the amount of water supplied from the first water tank  160 , an oscillator for generating steam  150  by applying a high frequency oscillation to the water stored in the second water tank  170  so that fine particles of the water can splash over the water surface, and a steam supply pipe  140  for discharging the steam generated by the oscillation of the oscillator  110 . 
         [0039]    As stated above, the first water tank  160  and second water tank  170  can be provided at the steam generating means so that the level of the water covering the oscillator, of the water supplied from the water supply device  80 , can be adjusted. This is because if the level of the water covering the oscillator  110  is too high due to a large amount of supplied water, the amount of the fine particles of the water emitted from the water surface may be decreased compared to the energy put to oscillate the oscillator  110  and thus the efficiency may be lowered. Accordingly, to overcome this problem, the steam generating means  100  may further include a water level control valve  120  consisting of a ball  124  and a spring  122  provided at the first water tank  160  and second water tank  170 . Since the opening and closing of the valve can be controlled according to a water pressure difference between the first water tank  160  and the second water tank  170  by using the water level control valve  120 , this enables the control of the water level of the second water tank  170 . However, the water level control valve  120  is not limited to the above-described means, but any of well known water level control valves capable of controlling the water level of the second water tank  170  can be used. 
         [0040]    The problem of water level control of the second water tank  170  can be overcome sufficiently by other means, including a method for restricting the level of water supplied by controlling of the water supply valve  82  provided at the water supply device  80  or controlling the height of the water tank. Therefore, it is not necessary to divide a water tank into two as illustrated in  FIG. 4  to implement the present invention. 
         [0041]    The oscillator  110  can fulfill its role only by transmitting ultrasonic waves to water to allow the fine particles of the water to be emitted from its surface, and there is no limitation in its shape or material. Also, although  FIG. 4  illustrates the oscillator as being installed as a single unit, a plurality of oscillators may be installed in order to increase the amount of steam generation. 
         [0042]    In the present invention, the method of generating steam by heating water up to a boiling point unlike the conventional art is not employed unlike the conventional art, but steam is generated in a manner that the fine particles of the water are ejected onto the water surface by the oscillation of the water molecules. Due to this, there is no need to raise the temperature of the water in order to generate steam, thus reducing the energy input amount for steam generation can be reduced, and there is no need to install a particular heat supplier for steam generation. Further, while the conventional steam generating means requires a waiting time because it generates steam after the water temperature reaches a boiling point, the present invention can shorten washing time because steam can be generated instantaneously when needed by using a means for generating steam by using ultrasonic waves. 
         [0043]    Although the steam generating means  100  is illustrated as having no particular heat supplier installed therein, the present invention is not limited thereto. Though there will be a problem of cost increase, a steam generating means having a heat supplier for use in the steam generating means installed therein is also included in the scope of the present invention as far as it has the features of the present invention. 
         [0044]    Hereinafter, the dryer  200  of the present invention and how the steam generated from the steam generating means  100  is generated and supplied into the washing tub  40  will be discussed. 
         [0045]    The dryer  200  includes a steam valve  250  for controlling steam supplied from the steam generating means  100 , an air intake valve  240  for sucking an outside air, a blower  210  for increasing the flow rate of the steam supplied from the steam valve  250  or of the air supplied from the air intake valve  240 , a drying duct  230  for inducing the flow of the steam or air whose flow rate is increased by the blower  210 . 
         [0046]    First, a procedure for drying laundry by the air dried by the dryer  200  will be described. As the blower  210  of the dryer  200  rotates, this forms a low pressure at the air intake valve side. At this time, air is permitted to be sucked through the air intake valve  240  by opening the air intake valve  240  and closing the steam valve  250 . The sucked air is heated by heat generated from the heat supplier  220  to thus lower the relative humidity, and the air is supplied into the washing tub  40  through the drying duct  230 . 
         [0047]    At this time, to dry laundry, air applied to the laundry should be dried as much as possible and its humidity should be lowered so that the air ejected to the laundry can dry the laundry by depriving the laundry of a sufficient amount of moisture. Due to this reason, it is necessary to prevent additional moisture from entering from the outside when reducing the relative humidity by sucking air and heating the air by the drier  200 . By the way, since the dryer  200  is communicatively connected to the steam generating means  100 , it is necessary to prevent the dryer  200  from sucking steam from the steam generating means when the dryer dries laundry. For this, it is preferable to perform a valve control such that the air intake valve  240  is opened and the steam valve  250  is closed in the procedure in which the dryer  200  supplies dried air to the washing tub  40 . However, if the heat supplier  230  supplies enough heat even if the air intake valve  240  or the steam valve  250  is not controlled, it is not impossible to maintain a sufficient humidity by drying air by the use of a heat supplier even if the steam generated in the steam generating means is partially included in the air during air intake. Moreover, if the dryer  200  is operated in a state that the operation of the steam generating means  100  is stopped, steam introduced from the steam generating means  100  during the drying process of the air may become smaller and hence there may be no big trouble in drying laundry. Thus, the air intake valve or the steam valve is not necessarily required. 
         [0048]    Although the blower  210  illustrated in  FIG. 5  employs the method of sucking air or steam by rotating wings, the present invention is not necessarily limited thereto, and any means capable of sucking air and steam, such as a gear pump and a piston pump, can be applied without any limitation. 
         [0049]    Further, although the heat supplier  220  may be a hot wire type as illustrated in  FIG. 5 , the present invention is not limited thereto and a heat pump or any other means capable of removing moisture by heating air can be applied. If there is a means capable of removing moisture from air by a chemical method, this means can replace the heat supplier  220 . Thus, it is not necessary to essentially provide the heat supplier  220 . 
         [0050]    Hereinafter, a procedure for heating steam supplied from the steam generating means through the dryer  200  will be described. First, as the blower  210  rotates, this lowers the pressure at the steam valve  250  side. At this time, if the air intake valve  240  is closed and the steam valve  250  is opened, steam is introduced through the steam valve  250  because no air is introduced from the air intake valve  240 . The introduced air passes through the heat supplier and is heated by receiving heat. 
         [0051]    At this time, to sufficiently raise the temperature of the steam, it is possible to use a means for increasing the opportunity to receive heat from the heat supplier  220  by making the length of the drying duct  230  and the surface area contacting the steam of the heat supplier  220  larger compared to those illustrated in  FIG. 5 , or by forming the passage of the drying duct so as to reciprocate the heat supplier  220  a number of times. Accordingly, the present invention is not limited by the arrangement of the drying duct  230  or hot wire as illustrated in  FIG. 5 . 
         [0052]    By the use of the steam generating means  100  of the present invention, a means for heating steam generated from the steam generating means  100  and a heater supplier, which is a means for heating air to dry laundry, can be integrated as the heat supplier  220  provided at the dryer  200 . Due to this, there is no particular heat supplier required in the steam generating means which has been essentially required in the prior art. As a result, it is possible to reduce costs enough to cover the expense of the heat supplier, thus increasing price competitiveness. Besides, the size of the steam generating means  100  can be drastically decreased, and this effect of decreasing the size of the steam generating means  100  makes it possible to additionally secure a space for other devices and significantly increase assembly workability. 
         [0053]    Although the present invention has been described in connection with the embodiment illustrated in the drawings, the embodiments are merely for illustrative purposes. It will be understood by those skilled in the art that various modifications and other equivalent embodiments can be made thereto. Therefore, the true technical scope of the invention should be construed as being defined by the appended claims.