Abstract:
A dishwasher is provided which uses a combined circulation/drain pump and an improved filtering system to enhance cleaning capability. The circulation section of the pump provides pressurization and supplies wash water to a spray arm of the dishwasher, while the drain section discharges the wash water. This single pump reduces space requirements, as well as manufacturing costs. A two stage filtration system may be used in the water collection area of the dishwasher to filter out unwanted material, and a third filter may further filter wash water prior to recirculation. Self cleansing mechanisms associated with each of the filters may be used to keep the filters free from obstructions and allow for the unobstructed flow and discharge of wash water.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a dishwasher, and more particularly, to a dishwasher having a simple structure and an improved function of filtering washing water. 
     2. Description of the Prior Art 
     A dishwasher is an appliance for automatically washing the dishes by spraying detergent-mixed washing water. The dishwasher having a variety of structures and shapes has been proposed. Hereinafter, the constitution of such conventional dishwasher will be briefly explained. 
     FIG. 1 is a view illustrating the constitution of the conventional dishwasher. 
     Referring to FIG. 1, the conventional dishwasher includes a case  10 , a rack  20  installed in the case  10  for accommodating the dishes, a spray arm  30  installed below the rack  20 , a circulation pump  40  for pressurizing and supplying washing water to the spray arm  30 , a drain pump  50  for draining the washing water, a filtering means for filtering the washing water, and the like. 
     Further, the spray arm  30  is horizontally rotatably supported by an arm holder  32  and is provided thereon with a plurality of spray nozzles  301  facing the rack  20 . Furthermore, the circulation pump  40  is constructed such that a discharge port thereof is connected to the arm holder  32  and an inlet port thereof is connected to a water collector  60  for constructing the filtering means. 
     The filtering means includes the water collector  60  disposed below a bottom surface of a case  10 , and a primary filter (coarse filter)  62  and a secondary filter (fine filter)  64  which are installed in the water collector  60 . A top face of the water collector  60  is opened toward a so-called washing space, a side face thereof is connected to the circulation pump  40 , and a bottom face thereof is connected to the drain pump  50 . The secondary filter  64  is constructed in the form of a pipe such that a lower part thereof can communicate with the drain pump  50 , and the primary filter  62  is constructed in the form of a filtering net provided within the secondary filter  64 . 
     The operation of the conventional dishwasher as described above can be broadly divided into a washing step and a drain step, and can be performed according to these steps. In the washing step, washing water in which pure water and detergent are mixed together is pressurized and supplied to the spray arm  30  by the circulation pump  40 . The washing water is then sprayed, through the spraying nozzles  301 , on the dishes d seated on the rack  20 . Consequently, the operation of washing the dishes d can be performed. Furthermore, in the drain step, the washing water can be discharged by the operation of the drain pump  50 . 
     FIG. 2 is a view illustrating a filtering process of the conventional dishwasher. 
     Referring to FIGS. 1 and 2, the washing and drain operations thereof will be explained in detail. As shown in FIG. 2, the washing water sprayed from the spray arm  30  is subject to a circulation operation that it is collected into the water collector  60  disposed on a lower portion of the case and then supplied again to the spray arm  30  by the circulation pump  40 . While the washing water is circulated, garbage such as food particles separated from the dishes d is filtered out or strained out by the primary and secondary filters  62 ,  64  installed in the water collector  60 , and thus, the washing water can be prevented from being dirty. Furthermore, at this time, the drain pump  50  should be not operating to prevent the washing water from draining. 
     The drain step progresses after the washing step for a predetermined period of time has been completed. In the drain step, the washing water is discharged by the operation of the drain pump  50 . At this time, a part of garbage particles that are large are filtered out by the primary filter  62  preventing a drain port from clogging. The filtered food particles remain in the primary filter  62 . Further, garbage, of which particles are small and has not been filtered by the primary filter  62  are filtered by the secondary filter  64 , and discharged together with the washing water through the drain port of the drain pump  50 . 
     While washing the dishes, a round of the washing/drain step can be performed by only a so-called single filling-up of the water. In general, during one round of washing the dishes, three or four times of filling-up of the water and subsequent washing/drain steps can be performed in order to enhance efficiency of washing the dishes. 
     However, the conventional dishwasher described above has required both the circulation pump  40  for use in the washing and rinsing processes and the drain pump  50  for use in the draining process. Therefore, there are problems in that the structure thereof is complex and the production costs thereof are high. 
     Further, according to the conventional dishwasher, the garbage adheres to the secondary filter  64  from the viewpoint of the structural nature of the secondary filter  64  (i.e., fine filter has fine meshes), and the garbage adhered thereto is not smoothly discharged during the drain step. Thus, newly supplied washing water may be contaminated. Accordingly, there are problems in that washing efficiency is reduced and the garbage adhered to the secondary filter deteriorates circulation efficiency of the newly supplied washing water. 
     Furthermore, after the washing process has been finally completed, the garbage filtered out by the respective filters  62 ,  64  should be removed. However, the garbage filtered out by the primary filter  62  is easily removed since the particles thereof are relatively large, whereas the fine garbage caught in the secondary filter  64  is not easily removed. Therefore, the problem that convenience of use is lowered is produced. 
     SUMMARY OF THE INVENTION 
     The present invention is contemplated to solve the above problems in the prior art. The present invention newly proposes a flow passage, a pump and a filtering structure of a dishwasher. To this end, the dishwasher of the present invention comprises a case; a rack installed in the case for accommodating the dishes; a spray arm installed below the rack for spraying washing water; a combined circulation/drain pump including an upper pump for repeatedly pressurizing and supplying the washing water to the spray arm and a lower pump for discharging the washing water; and a filtering means for filtering the washing water, which includes a water collector formed below a bottom surface of the case and in a washing water flow passage connected to the combined circulation/drain pump, a filter provided in the water collector for filtering out garbage, a filter self-cleansing means for performing self-cleansing operation of the filter, a garbage collecting chamber that is provided below the bottom surface of the case and is connected to both a washing water discharge port of the upper pump and a drain flow passage of the lower pump, a fine filter mounted on a top surface of the garbage collecting chamber for filtering out the garbage from the washing water discharged upward, and a fine filter self-cleansing means for performing self-cleansing operation of the fine filter. 
     According to the dishwasher of the present invention, there is an advantage in that a user can more conveniently utilize the dishwasher, since the filtering means having the self-cleansing means installed therein is employed in the dishwasher. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view illustrating the constitution of a conventional dishwasher. 
     FIG. 2 is a view illustrating a filtering process of the conventional dishwasher. 
     FIG. 3 is a perspective view of a dishwasher according to an embodiment of the present invention. 
     FIG. 4 is a vertical sectional view of a combined circulation/drain pump employed in the dishwasher according to the embodiment of the present invention. 
     FIGS. 5 a,    5   b  and  5   c  are views illustrating operations of the combined circulation/drain pump employed in the dishwasher according to the embodiment of the present invention. 
     FIG. 6 is a view illustrating a washing water circulation flow path of the dishwasher of the present invention. 
     FIGS. 7 a  and  7   b  are views illustrating operations of a fine filter employed in the dishwasher according to the embodiment of the present invention. 
     FIG. 8 is a horizontal sectional view of a garbage collecting chamber, for illustrating the operation of a dispersing means of the fine filter according to the embodiment of the present invention. 
     FIG. 9 is a vertical sectional view of the garbage collecting chamber, for illustrating the operation of the dispersing means of the fine filter according to the embodiment of the present invention. 
     FIG. 10 a  is a view illustrating a state of a water collector and the like during the washing operation according to the embodiment of the present invention. 
     FIG. 10 b  is a view illustrating a state of the water collector and the like during the drain operation according to the embodiment of the present invention. 
     FIG. 11 a  is a view illustrating an operation of an upper pump during the washing operation according to the embodiment of the present invention. 
     FIG. 11 b  is a view illustrating an operation of the upper pump during the drain operation according to the embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 3 to  9  of the accompanying drawings. 
     A dishwasher according to an embodiment of the present invention includes a combined circulation/drain pump  70  for pressurizing and supplying washing water to a spray arm  30  and for draining the washing water; and a filtering means for filtering the washing water. 
     As shown in FIG. 4, the combined circulation/drain pump  70  includes a driving motor  72 ; a pump casing  74  of which inner space is divided into a circulating section  741  and a drain section  742 ; and upper and lower pumps  76 ,  78  disposed in the circulating section  741  and the drain section  742  of the pump casing  74 , respectively, and connected to a rotating shaft of the driving motor  72  so as to make a flow of the washing water. In particular, it is preferable that a centrifugal pump should be used for the upper pump  76  and a friction pump be used for the lower pump  78 . 
     Here, the upper and lower pumps  76 ,  78  are in charge of the supply and drain of water, respectively. The circulating section  741  of the pump casing  74  is formed with a washing water inlet port  74   a  and a washing water discharge port  74   b,  and the drain section  742  is formed with a drain inlet port  74   c  and a drain discharge port  74   d  (see FIG. 5 a ). 
     Further, the filtering means includes a water collector  80  provided below a bottom surface of a case  10  and located in a washing water flow passage drawn into the combined circulation/drain pump  70 ; a primary filter  82  and a secondary filter  81  (see FIG. 10 a ) provided in the water collector  80 ; a garbage collecting chamber  90  provided below the bottom surface of the case  10 ; a fine filter  92  mounted on a top surface of the garbage collecting chamber  90 ; and a fine filter self-cleansing means for performing a self-cleansing operation of the fine filter  92 . Moreover, the primary and secondary filters  82 ,  81  may also be provided with a self-cleansing means, which will be described later. 
     The primary filter  82  is a coarse filter formed in a shape of a basket similar to a conventional filter and filters a part of garbage having relatively large particles. The fine filter  92  is a plate-shaped filter having meshes finer than those of the primary filter  82  and strains out garbage having relatively small particles. 
     Furthermore, the fine filter self-cleansing means includes an auxiliary nozzle  302  (see FIG. 7) provided on a bottom surface of the spray arm  30  so that garbage adhered to the fine filter  92  is separated therefrom by spraying the washing water downward. The auxiliary nozzle  302  is spaced apart at a predetermined distance from the center of rotation of the spray arm  30  so that they pass over the fine filter  92  upon rotation of the spray arm. 
     The operation of the dishwasher according to the embodiment of the present invention as described above will be explained below. 
     First, in a washing process, the washing water in which pure water and detergent are mixed is fed by the combined circulation/drain pump  70  to the spray arm  30  through the washing water discharge port  74   b  and is then sprayed from the spray nozzles  301  to the dishes d seated on a rack  20 . Thus, an operation of washing the dishes d is made. 
     That is, as shown in FIG. 5 a,  the upper pump  76  connected to the washing water flow passage rotates in a clockwise direction so that the washing water (designated by a bold arrow in the figure) can flow through the washing water inlet port  74   a  into the circulating section  741  of the pump casing  74 . Then, the drawn washing water is pressurized and discharged toward the spray arm  30  by the upper pump  76 . 
     At this time, as shown in FIG. 5 b,  the lower pump  78  rotates in the same direction as the upper pump  76  so that it applies suction force to the drain discharge port  74   d  and discharging force to the drain inlet port  74   c.  Therefore, an operation of introducing the washing water into the drain section  742  through the drain inlet port  74   c  is not made. 
     In addition, in a drain process to be performed after completion of the washing process, since the combined circulation/drain pump  70  rotates in a direction opposite to that of the pump  70  in the washing process, i.e. counterclockwise direction, the lower pump  78  also rotates in the counterclockwise direction, as shown in FIG. 5 c.  Therefore, suction force is applied to the drain inlet port  74   c  and discharging force is applied to the drain discharge port  74   d,  so that the washing water is drained through the drain section  742  and discharging force from the upper pump  76  is applied to the washing-water inlet port  74   a  of the circulating section  741 . Thus, an operation of circulating the washing water is not made. 
     In the washing and drain processes, an operation of filtering the washing water is also made by the filtering means. The operation of filtering the washing water is divided into a main filtering operation by means of the primary and secondary filters  82 ,  81  and an auxiliary filtering operation by means of the fine filter  92 . 
     The main filtering operation by means of the primary and secondary filters  82 ,  81  is made in such a manner that while the washing water sprayed from the spray arm  30  is circulated once, all the washing water passes through both the primary and secondary filters  82 ,  81  and garbage mixed with the washing water is then strained out. 
     The auxiliary filtering operation by means of the fine filter  92  is made in such a manner that a portion of the washing water discharged from the combined circulation/drain pump  70  flows through a branched flow passage  74   e  into the garbage collecting chamber  90  below the fine filter  92  before it flows into the spray arm  30 , as shown in FIG. 6, and is then spouted upward from the fine filter  92  (see FIG. 7) so that garbage having fine particles, which has not been filtered out by the primary filter  82 , can be strained out by the fine filter  92 . 
     In a case where the circulation of the washing water is repeated predetermined times in the washing process, since there is the same effect that the total amount of washing water that has been fed once has passed through the fine filter  92 , garbage having fine particles contained in the washing water is completely strained out. 
     On the other hand, in the washing process, the spray arm  30  sprays the washing water through a plurality of spray nozzles  301  directed upward in order to clean the dishes. As shown in FIG. 7 a,  the spray arm  30  is formed with the auxiliary nozzle  302  that spray the washing water downward. The downward sprayed washing water intermittently strikes the top surface of the fine filter  92  so that foreign materials adhered to a bottom surface of the fine filter  92  are removed. That is, the so-called self-cleansing function is performed. 
     Thus, the garbage trapped in the garbage collecting chamber  90  is maintained in a floating state therein by means of the aforementioned self-cleansing function, so that the fine filter  92  is prevented from being partially clogged with the garbage adhered thereto. 
     Referring to FIG. 7 b,  when a drain process proceeds after the completion of the washing process, the garbage trapped in the garbage collecting chamber  90  can be smoothly discharged together with the washing water through a drain flow passage  74   f.  Therefore, it is not necessary to additionally clean the fine filter  92  after the washing process of the dishes has been completed. 
     According to another embodiment of the present invention, there is further provided a dispersion means for preventing the garbage from intensively building up just at the one side of the fine filter  92  (particularly, a side opposite to the inflow side) due to the flow of the washing water by dispersing the flow of the washing water introduced into the garbage collecting chamber  90 . The dispersion means includes a plurality of baffles  94  alternately placed at a predetermined distance from each other within the garbage collecting chamber  90 , as shown in FIG.  8 . 
     In a case where such dispersion means is provided, since the strong flow of the washing water introduced into the garbage collecting chamber  90  by means of the pressurizing operation of the combined circulation/drain pump  70  is blocked and dispersed by a plurality of baffles  94 , the washing water can be uniformly discharged throughout the entire area of the fine filter  92 , thereby the garbage is more effectively filtered. 
     Therefore, the garbage contained in the washing water is also uniformly filtered in the entire portion of the fine filter  92 , and thus, the self-cleansing function by the washing water sprayed from the auxiliary nozzle  302  can be more effectively performed. 
     Hereinafter, a structure of a filter self-cleansing means for further enhancing the effect of garbage filtration in an embodiment of the present invention will be explained. 
     FIG. 10 a  is a view illustrating a state of the water collector etc. during the washing process in this embodiment; FIG. 10 b  is a view illustrating a state of the water collector etc. during the drain process of this embodiment; FIG. 11 a  is a view illustrating the operation of the upper pump during the washing process of this embodiment; and FIG. 11 b  is a view illustrating the operation of the upper pump during the drain process of this embodiment. 
     Referring to FIGS. 10 a  to  11   b,  the dishwasher according to the embodiment of the present invention includes the filter self-cleansing means that separates foreign materials adhered to inner surfaces of the primary and secondary filter  82 ,  81  within the water collector  80  therefrom by spraying the washing water pressurized by the combined circulation/drain pump  70  during the drain operation. 
     The filter self-cleansing means includes a foreign material washing nozzle  84 ; an auxiliary discharge pipe  74   g  for connecting the upper pump  76  of the combined circulation/drain pump  70  to the foreign material washing nozzle  84 ; and a blocking barrier  79  (see FIG. 11 a ) mounted on an inlet side of the auxiliary discharge pipe  74   g.    
     Here, the foreign material washing nozzle  84  is placed facing the primary and secondary filters  82 ,  81  such that the washing water is sprayed from the outside to the inside of the filters. The blocking barrier  79  is configured as a structure in the shape of a triangular block of which one vertex is pivotably connected to a portion adjacent the inlet of the auxiliary discharge pipe  74   g,  and is pivoted by means of the stream of water according to the rotational direction of the upper pump  76 . Thus, it can open and close the inlet of the auxiliary discharge pipe  74   g.    
     Particularly, in order to effectively perform the self-cleansing of the filter, it is preferred that the foreign material washing nozzle  84  is installed on a side of the washing water inlet port  74   a  in which garbage is mainly caught during the washing operation. 
     The operation of the dishwasher according to this embodiment constructed as such will be described below. 
     First, in the combined circulation/drain pump  70  during the washing operation, the upper pump  76  rotates in the clockwise direction, so that the blocking barrier  79  is pivoted on the pivotably connected vertex in the counterclockwise direction by means of the stream of water made within the upper pump  76  and blocks the inlet of the auxiliary discharge pipe  74   g.  Thus, the washing water is not sprayed through the foreign material washing nozzle  84 , but it is sprayed only through the spray arm  30  (see FIG. 11 a ). 
     Further, garbage contained in the washing water is strained out by the primary and secondary filters  82 ,  81  while passing through the water collector  80 . The washing water from which the garbage is removed is drawn into the combined circulation/drain pump  70  through the washing water inlet port  74   a.  At this time, the garbage in the primary and secondary filters  82 ,  81  is intensively collected on the side of the washing water inlet port  74   a  (see FIG. 10 a ). 
     On the other hand, in the drain operation, since the upper pump  76  rotates in the counterclockwise direction opposite to that of the pump  76  during the washing operation, the stream of water made within the upper pump  76  also flows in a direction opposite to that of the stream during the washing operation. The change in the stream of water causes the blocking barrier  79  to be pivoted on the vertex in the clockwise direction so that the inlet of the auxiliary discharge pipe  74   g  is opened and the washing water is supplied through the foreign material washing nozzle  84  (see FIG. 11 b ). Although pressure applied to the auxiliary discharge pipe  74   g  during the drain operation is lower than pressure applied to the pipe  74   g  by means of the upper pump  76  during the washing operation, it is sufficient to separate the foreign material adhered to the primary and secondary filters  82 ,  81  therefrom. 
     In addition, the washing water is pressurized by the upper pump  76  and supplied to the foreign material washing nozzle  84  through the auxiliary discharge pipe  74   g.  The foreign material washing nozzle  84  sprays the supplied washing water toward the primary and secondary filters  82 ,  81  and separates the foreign material adhered to the inner surfaces of the filters  82 ,  81  therefrom (see FIG. 10 b ). 
     Further, the foreign materials separated from the filters  82 ,  91  by the foreign material washing nozzle  84  are smoothly discharged together with the drained washing water through the drain discharge port  74   c.  Thus, the washing water to be fed again does not further get dirty and the circulation efficiency of the washing water to be fed again is not deteriorated. 
     As described above, according to the dishwasher of the present invention, there are advantages as follows. 
     First, since the combined circulation/drain pump for performing both the circulation and the drain of the washing water is provided, the structure of the dishwasher is simplified and production costs are lowered. Second, since the foreign materials strained out by the fine filter during the washing process are smoothly discharged during the drain process, the washing water to be fed again dose not get dirtier. Third, since the fine filter is self-cleansed, an additional cumbersome operation for removing the foreign materials after washing the dishes is not required. Fourth, since the garbage can be more effectively discharged by employing the foreign material washing nozzle, the washing water is prevented from getting dirtier and the circulation efficiency of the washing water is enhanced. Consequently, the productivity, the function, and the convenience of use thereof are improved.