Method of controlling dishwasher and dishwasher

Abstract

A dishwasher and method of controlling a dishwasher are provided. In the dishwasher and the method, a heater in a sump begins to be driven when a measured fluid supply frequency measured before the supply of wash fluid into the sump is complete reaches a predefined value, and thus heats the wash fluid in the sump. Thus, it is possible to reduce the time taken to heat the wash fluid in the sump to a target temperature, thus reducing the operating time of the dishwasher.

1 . A method of controlling a dishwasher, the method comprising:
 supplying wash fluid into a sump until a flow rate of the wash fluid measured by a flow rate detector reaches a first set value; and   heating the wash fluid in the sump by operating a heater when the flow rate of the wash fluid measured by the flow rate detector reaches a second set value, the second set value being less than the first set value.   
   
   
       2 . The method of  claim 1 , wherein the heater is positioned at a bottom portion of the sump and the second set value is based on a point at which the heater begins to be immersed in wash fluid. 
   
   
       3 . The method of  claim 1 , wherein the first set value is between approximately 150 and 250 Hz. 
   
   
       4 . The method of  claim 1 , wherein heating the wash fluid comprises heating the wash fluid in the sump until a fluid temperature in the sump reaches a target temperature. 
   
   
       5 . The method of  claim 1 , wherein the flow rate detector comprises a flowmeter, and wherein supplying wash fluid into a sump comprises measuring the flow rate of wash fluid supplied into the sump as the flow of wash fluid rotates the flowmeter. 
   
   
       6 . The method of  claim 1 , wherein the flow rate detector comprises a pressure switch provided in the sump to measure a fluid pressure in the sump. 
   
   
       7 . A dishwasher, comprising:
 a sump;   a supply device that supplies wash fluid to the sump;   a heater that heats the wash fluid in the sump; and   a controller that controls the heater to heat the wash fluid in the sump as wash fluid is supplied to the sump.   
   
   
       8 . The dishwasher of  claim 7 , further comprising a flow rate detector that measures a flow rate of wash fluid supplied to the sump, wherein the controller determines when to operate the heater based on the measured flow rate provided by the flow rate detector. 
   
   
       9 . The dishwasher of  claim 8 , wherein the flow rate detector comprises:
 an impeller that is rotated by incoming wash fluid; and   a magnet that generates a magnetic field as the impeller rotates.   
   
   
       10 . The dishwasher of  claim 9 , wherein the controller converts a pulse that corresponds to the magnetic field generated by the magnet, into a supply frequency that corresponds to the measured flow rate. 
   
   
       11 . The dishwasher of  claim 8 , wherein the controller supplies wash fluid to the sump until the flow rate measured by the flow rate detector reaches a first set value, and wherein the controller heats the wash fluid in the sump by operating a heater when the flow rate measured by the flow rate detector reaches a second set value. 
   
   
       12 . The dishwasher of  claim 11 , wherein the second set value is less than the first set value. 
   
   
       13 . The dishwasher of  claim 11 , wherein the second set value is based on a point at which the heater begins to be immersed in wash fluid. 
   
   
       14 . The dishwasher of  claim 11 , wherein the controller operates the heater for a first set time, and terminates operation of the heater for a second set time after the first set time has elapsed when the flow rate measured by the flow rate detector reaches the second set value. 
   
   
       15 . The dishwasher of  claim 11 , wherein the controller operates the heater when the flow rate detector determines that wash fluid is being supplied to the sump. 
   
   
       16 . The dishwasher of  claim 7 , wherein the controller measures an amount of time taken to supply wash fluid to the sump and operates the heater when the measured amount of time exceeds a predefined amount. 
   
   
       17 . A method of controlling a dishwasher, the method comprising:
 supplying wash fluid to a sump;   measuring a flow rate of the wash fluid as it is supplied to the sump, and comparing the measured flow rate to a first set value and a second set value;   turning on a heater and heating the was fluid collected in the sump when the measured flow rate is greater than or equal to the second set value; and   continuing to supply wash fluid to the sump while the heater heats the wash fluid collected in the sump until the measured flow rate is equal to the first set value.   
   
   
       18 . The dishwasher of  claim 17 , wherein measuring a flow rate of the wash fluid comprises:
 directing the wash fluid across an impeller to rotate the impeller;   generating a magnetic field using at least one, magnet in response to the rotation of the impeller; and   generating a fluid supply frequency based on the magnetic field generated by the at least one magnet that corresponds to a flow rate of the wash fluid being supplied to the sump.   
   
   
       19 . The dishwasher of  claim 18 , wherein turning on a heater and heating the wash fluid collected in the sump when the measured flow rate is greater than or equal to the second set value comprises turning on the heater when the fluid supply frequency is greater than or equal to the second set value, wherein a fluid supply frequency of the second set value corresponds to a point at which the heater is immersed in the wash fluid collected in the sump. 
   
   
       20 . The dishwasher of  claim 19 , wherein continuing to supply wash fluid to the sump while the heater heats the wash fluid collected in the sump until the measured flow rate is equal to the first set value comprises supplying wash fluid to the sump until the fluid supply frequency is equal to the first set value, wherein a fluid supply frequency of the first set value corresponds to a point at which the sump is at a predefined fill level required for a selected operation of the dishwasher. 
   
   
       21 . The dishwasher of  claim 20 , further comprising continuing to heat the wash fluid collected in the sump until a temperature thereof is greater than or equal to a target temperature, and then shutting off the heater. 
   
   
       22 . The dishwasher of  claim 21 , further comprising intermittently turning the heater on and off to maintain the wash fluid collected in the sump at the target temperature.