Method for operating a laundry treatment machine and laundry treatment machine

Abstract

A method for operating a laundry treatment machine having a container for housing a laundry load to be treated and a pump. The pump has an electric motor adapted to be powered by a motor voltage (VMOT) and a motor current (IMOT). An air-water working condition of the pump is detected/evaluated based on values of the motor voltage (VMOT) and/or the motor current (IMOT) of the electric motor.

1 . A method for operating a laundry treatment machine comprising a container for housing a laundry load to be treated and a pump comprising an inlet for a liquid suction and an electric motor, the method comprising:
 applying a motor voltage (VMOT) and a motor current (IMOT) to the electric motor to drive the pump; and   detecting an air-water working condition of the pump based on a respective value of at least on of the motor voltage (VMOT) and the motor current (IMOT).   
     
     
         2 . The method according to  claim 1 , wherein detecting the air-water working condition of the pump comprises detecting signal indicative of a condition caused by the presence of air at the inlet of the pump. 
     
     
         3 . The method according to  claim 1 , wherein the electric motor is connected to a mains power supply providing a sinusoidal mains voltage (VMAINS). 
     
     
         4 . The method according to  claim 3 , wherein the motor voltage (VMOT) applied to the electric motor is a partialized version of the sinusoidal mains voltage (VMAINS). 
     
     
         5 . The method according to  claim 4 , wherein detecting the air-water working condition comprises detecting when a root-mean-square voltage (VMOTrms) of the motor voltage (VMOT) deviates from a threshold value (TV). 
     
     
         6 . The method according to  claim 5 , wherein detecting the air-water working condition comprises detecting when the root-mean-square voltage (VMOTrms) of the motor voltage (VMOT) is above or below the threshold value (TV). 
     
     
         7 . The method according to  claim 4 , wherein detecting the air-water working condition comprises detecting when an activation time (TIon) of the motor current (IMOT) deviates from a threshold value (TI). 
     
     
         8 . The method according to  claim 7 , wherein the activation time (TIon) is a period of time starting when the motor current (IMOT) increases or decreases from 0 and ending when the motor current (IMOT) crosses again 0. 
     
     
         9 . The method according to  claim 7 , wherein detecting the air-water working condition comprises detecting when the activation time (TIon) is above or below the threshold value (TI). 
     
     
         10 . The method according to  claim 3 , wherein detecting the air-water working condition comprises detecting when a phase difference (Td) between the motor voltage (VMOT) and the motor current (IMOT) deviates from a threshold value (TT). 
     
     
         11 . The method according to  claim 1 , further comprising, subsequent to detecting the air-water working condition performing one or more of:
 deactivating the pump;   deactivating the pump immediately after the air-water working condition is detected;   deactivating the pump after a predetermined period after the air-water working condition is detected;   changing a speed of the pump;   reducing a speed of the pump;   temporarily changing a speed of the pump;   temporarily reducing a speed of the pump; and   increasing a level of a liquid at the inlet of the pump.   
     
     
         12 . The method according to  claim 1 , further comprising, subsequent to detecting the air-water working condition performing one or more of:
 introducing a quantity of water into a washing tub external to the container, from an external water supply line;   increasing a level of a liquid at the inlet of the pump by performing a spinning phase by rotating the container in order to extract liquid from the laundry, in case the container is not moving; and   increasing a rotating speed of the container, in case the container is already rotating.   
     
     
         13 . A laundry treatment machine comprising:
 at least one pump comprising an inlet for a liquid suction and an electric motor adapted to be powered by a motor voltage (VMOT) and a motor current (IMOT);   a control unit configured to determine an air-water working condition by detecting the motor voltage (VMOT) and/or the motor current (IMOT) during operation of the pump.   
     
     
         14 . The laundry treatment machine according to  claim 13 , wherein the machine comprises a laundry washing machine or a laundry washing/drying machine or a laundry drying machine. 
     
     
         15 . The laundry treatment machine according to  claim 13 , wherein the laundry treatment machine is a laundry washing machine comprising a washing tub external to the container and wherein the pump is a pump of one or more of the following parts of the machine:
 a water softening device;   a water outlet circuit configured to a liquid outside the machine;   a recirculation circuit configured to drain a liquid from a bottom region of the washing tub and re-admit the liquid into the washing tub; and   a treatment agents dispenser.