Dishwasher and method of operation

Abstract

A dishwasher includes an interior tub and a wash pump for pumping wash liquid to wash dishes located in the interior tub. A pump motor for driving the wash pump is regulated by a control unit that adjusts a spraying pressure of wash liquid. The method for operating a dishwasher includes sensing the degree to which wash liquid is soiled and regulating the speed of a pump motor for spraying wash liquid against the dishes, depending upon the degree to which the wash liquid is soiled. The regulation of the pump motor adjusts the wash liquid spraying pressure.

What is claimed:  
     
         1 . A dishwasher comprising: 
 an interior tub in which dishes to be washed are located;    a wash pump for pumping wash liquid for washing the dishes located in the interior tub;    a pump motor for driving the wash pump;    spraying means for spraying wash liquid onto the dishes; and    a control unit for regulating the speed of the pump motor to adjust a spraying pressure of wash liquid sprayed from the spraying means.    
     
     
         2 . The dishwasher as set forth in  claim 1 , wherein the control unit regulates the speed of the pump motor by controlling a phase of power inputted to the pump motor.  
     
     
         3 . The dishwasher as set forth in  claim 1 , further comprising a sensor for sensing the degree to which the wash liquid is soiled, upon washing the dishes.  
     
     
         4 . The dishwasher as set forth in  claim 3 , wherein the sensor senses a soil concentration in the wash liquid and calculates a rate of concentration change of the wash liquid.  
     
     
         5 . The dishwasher as set forth in  claim 4 , wherein when a sensed soil concentration in the wash liquid is constant and the calculated rate of concentration change is lower than a previous value, the control unit implements a next dishwashing procedure.  
     
     
         6 . The dishwasher as set forth in  claim 2 , wherein the control unit comprises: 
 a microcomputer for generating and outputting a trigger signal to control the supply of power from a power source to the pump motor; and    a phase controlling driver circuit for controlling a phase of power to be supplied from the power source to the pump motor in response to the trigger signal generated and outputted by the microcomputer,    wherein the phase controlling driver circuit applies a resulting power to the pump motor.    
     
     
         7 . The dishwasher as set forth in  claim 6 , wherein the microcomputer controls the phase controlling driver circuit so that a first speed of the pump motor, when a sensed soil concentration is higher than a reference value, is greater than a second speed of the pump motor when a sensed soil concentration is lower than the reference value, wherein a first wash liquid spraying pressure is associated with the first speed and a second wash liquid spraying pressure is associated with the second speed and the first liquid spraying pressure is greater than the second liquid spraying pressure.  
     
     
         8 . The dishwasher as set forth in  claim 1 , further comprising a spraying pressure adjustment control for allowing an operator to regulate the speed of the pump motor.  
     
     
         9 . A method for operating a dishwasher, comprising: 
 sensing a degree to which wash liquid is soiled, upon washing the dishes;    regulating a speed of a pump motor for spraying wash liquid onto dishes in the dishwasher, the regulation depending upon the degree to which wash liquid is soiled as sensed during the sensing; and    adjusting a wash liquid spraying pressure depending upon the speed of the pump motor.    
     
     
         10 . The method as set forth in  claim 9 , further comprising determining the degree of soil concentration in the wash liquid and calculating a rate of concentration change of the wash liquid.  
     
     
         11 . The method as set forth in  claim 10 , further comprising implementing a next dishwashing procedure when the sensed soil concentration is constant and the calculated rate of concentration change is lower than a previous value.  
     
     
         12 . The method as set forth in  claim 9 , wherein the speed of the pump motor is regulated such that a first level of power inputted to the pump motor, when a sensed soil concentration is higher than a reference value, is greater than a second level of power inputted to the pump motor when a sensed soil concentration is lower than the reference value.  
     
     
         13 . The method as set forth in  claim 9 , further comprising receiving an instruction from an operator to adjust the wash liquid spraying pressure, 
 wherein the speed of the pump motor is regulated in response to the instruction for adjusting the wash liquid spraying pressure.