Dishwasher and controlling method therefor

Abstract

The present invention relates to a dishwasher for washing the dishes and the cooking utensils by spraying washing water, and a control method thereof. The control method of a dishwasher according to an embodiment of the present invention includes: a water supply step of opening a water supply valve to supply washing water to the sump; and a variable spray step of spraying the washing water by at least one of the plurality of spray arms by changing the number of revolutions of the washing pump stepwise, so that the washing water can be sprayed evenly.

What is claimed is: 
     
         1 . A method of controlling a dishwasher that includes a tub configured to receive a washing object, a plurality of spray arms configured to spray washing water to the tub, a sump configured to store washing water, and a washing pump configured to pump washing water stored in the sump to the plurality of spray arms, the method comprising:
 supplying washing water by opening a water supply valve of the dishwasher; and   spraying washing water through at least one of the plurality of spray arms based on changing a number of revolutions of the washing pump by one or more levels.   
     
     
         2 . The method of  claim 1 , wherein changing the number of revolutions of the washing pump comprises increasing the number of revolutions of the washing pump by one or more increment levels and decreasing the number of revolutions of the washing pump in one or more decrement levels, and
 wherein decreasing the number of revolutions of the washing pump comprises repeatedly decreasing the number of revolutions of the washing pump in the one or more decrement levels after increasing the number of revolutions of the washing pump by the one or more increment levels.   
     
     
         3 . The method of  claim 2 , wherein a number of the one or more decrement levels is equal to a number of the one or more increment levels. 
     
     
         4 . The method of  claim 1 , wherein changing the number of revolutions of the washing pump comprises maintaining the number of revolutions of the washing pump for a constant period at each level of the one or more levels. 
     
     
         5 . The method of  claim 4 , wherein the plurality of spray arms comprises a first spray arm that has a bar shape and that is configured to rotate, and
 wherein maintaining the number of revolutions of the washing pump for the constant period comprises maintaining the number of revolutions of the washing pump for a duration that is greater than or equal to a maximum time period during which the first spray arm rotates once.   
     
     
         6 . The method of  claim 4 , wherein the plurality of spray arms comprises a first spray arm that has a bar shape and that is configured to rotate and spray washing water, and
 wherein maintaining the number of revolutions of the washing pump for the constant period comprises maintaining the number of revolutions of the washing pump for a duration that is greater than or equal to a rotation period corresponding to one rotation of the first spray arm at a minimum number of revolutions of the washing pump.   
     
     
         7 . The method of  claim 1 , wherein changing the number of revolutions of the washing pump by the one or more levels comprises:
 increasing the number of revolutions of the washing pump by a step width corresponding to a difference in the number of revolutions between two adjacent levels among a plurality of levels; and   decreasing the number of revolutions of the washing pump by the step width.   
     
     
         8 . The method of  claim 1 , wherein the plurality of spray arms comprises an upper spray arm disposed at the tub, and
 wherein spraying washing water through at least one of the plurality of spray arms comprises supplying, by the washing pump, washing water to the upper spray arm.   
     
     
         9 . The method of  claim 8 , wherein the upper spray arm has a bar shape and is configured to rotate, and
 wherein spraying washing water comprises spraying washing water based on changing a rotation speed of the upper spray arm by one or more speed steps.   
     
     
         10 . The method of  claim 8 , wherein spraying washing water comprises spraying washing water based on changing a spray direction of washing water sprayed from the upper spray arm in one or more direction steps. 
     
     
         11 . The method of  claim 8 , further comprising:
 supplying, by operating the washing pump, washing water stored in the sump to a top spray arm among the plurality of spray arms, the top spry arm being disposed at an upper portion of the tub and being configured to spray washing water in a downward direction; and   supplying, by operating the washing pump, washing water stored in the sump to a lower spray arm among the plurality of spray arms, the lower spray arm being disposed at a lower portion of the tub and being configured to spray washing water in an upward direction, and   wherein changing the number of revolutions of the washing pump comprises changing the number of revolutions of the washing pump to a range (i) that is less than or equal to a maximum number of revolutions of the washing pump at which the washing pump operates to supply washing water to the top spray arm and (ii) that is greater than or equal to a maximum number of revolutions of the washing pump at which the washing pump operates to supply washing water to the lower spray arm.   
     
     
         12 . The method of  claim 1 , further comprising:
 maintaining the number of revolutions of the washing pump after changing the number of revolutions of the washing pump; and   stopping operation of the washing pump and draining washing water stored in the sump to an outside of the sump after maintaining the number of revolutions of the washing pump.   
     
     
         13 . The method of  claim 12 , wherein maintaining the number of revolutions of the washing pump comprises maintaining the number of revolutions of the washing pump at an average value of the number of revolutions of the washing pump of the one or more levels. 
     
     
         14 . The method of  claim 1 , further comprising heating washing water supplied to the sump,
 wherein spraying washing water comprises spraying heated washing water through at least one of the plurality of spray arms.   
     
     
         15 . The method of  claim 14 , further comprising:
 mixing washing water supplied from an external water source with a rinsing detergent;   spraying the mixed washing water through at least one of the plurality of spray arms and then draining the mixed washing water; and   based on spraying the mixed washing water and draining the mixed washing water, performing a heat rinsing process that comprises supplying washing water to the sump, heating washing water supplied to the sump, and spraying heated washing water through at least one of the plurality of spray arms based on changing the number of revolutions of the washing pump by the one or more levels.   
     
     
         16 . A dishwasher comprising:
 a tub configured to accommodate a washing object;   a plurality of spray arms that are arranged at one or more vertical positions in the tub and that are configured to spray washing water into the tub;   a sump configured to store washing water;   a washing pump configured to supply washing water stored in the sump to at least one of the plurality of spray arms, the washing pump comprising a washing motor;   a heater configured to heat washing water supplied to the sump; and   a controller configured to control the washing pump and the heater,   wherein the controller is configured to, based on operating the heater and changing a number of revolutions of the washing motor by one or more levels, spray washing water through at least one of the plurality of spray arms.   
     
     
         17 . The dishwasher of  claim 16 , wherein the controller is further configured to repeatedly decrease the number of revolutions of the washing pump by one or more decrement levels after increasing the number of revolutions of the washing pump by one or more increment levels. 
     
     
         18 . The dishwasher of  claim 16 , wherein the controller is configured to change the number of revolutions of the washing pump by a constant step width corresponding to a difference in the number of revolutions between two adjacent levels among a plurality of levels. 
     
     
         19 . The dishwasher of  claim 16 , further comprising a switching valve configured to selectively connect the washing pump to at least one of the plurality of spray arms,
 wherein the plurality of spray arms comprise an upper spray arm disposed at an intermediate portion of the tub, and   wherein the controller is further configured to control the switching valve to connect the washing pump to the upper spray arm based on changing the number of revolutions of the washing motor in the one or more levels.   
     
     
         20 . The dishwasher of  claim 16 , further comprising a drain pump configured to drain washing water stored in the sump to an outside of the sump,
 wherein the controller is configured to:
 change the number of revolutions of the washing motor in the one or more levels and then maintain the number of revolutions of the washing motor, and 
 stop operation of the washing motor and then operate the drain pump.