Laundry washing machine and method for operating the laundry washing machine

Abstract

A laundry washing machine having a washing drum, a washing tub external to the washing drum and a recirculation system having a first duct terminating at a first region of the washing tub and a second duct terminating at a second region of the washing tub. The recirculation system comprises a recirculation pump for conveying liquid to a bifurcation for the first duct and the second duct. The recirculation pump has a first functioning condition wherein liquid circulates only in the first duct and a second functioning condition wherein liquid circulates both in the first and second ducts.

1 . A laundry washing machine comprising:
 a washing drum configured to receive laundry to be washed;   a washing tub external to the washing drum;   a water supply system configured to convey water to the washing tub; and   a recirculation system configured to drain a liquid from the bottom of the washing tub and to re-admit the liquid into a first region and a second region of the washing tub, the recirculation system comprising:
 a first duct terminating at the first region wherein the liquid may circulate to reach the washing tub, 
 a second duct terminating at the second region wherein the liquid may circulate to reach the washing tub, and 
 a recirculation pump having an inlet connected to the bottom of the washing tub and an outlet at a bifurcation leading to the first duct and the second duct, 
 wherein the first duct and the second duct are configured so that the liquid in the first duct requires a first pressure to reach the washing tub which is lower than a second pressure required for the liquid in the second duct to reach the washing tub, and 
 the recirculation pump has a first functioning condition wherein the liquid circulates only in the first duct to reach the washing tub and a second functioning condition wherein liquid circulates both in the first and the second duct to reach the washing tub. 
   
     
     
         2 . The washing machine according to  claim 1 , wherein the recirculation pump is a variable-speed pump, wherein in the first functioning condition the recirculation pump is driven at a first speed and in the second functioning condition the recirculation pump is driven at a second speed, the second speed being higher than the first speed. 
     
     
         3 . The washing machine according to  claim 1 , wherein the recirculation pump is driven so that its speed has a pulsed waveform. 
     
     
         4 . The washing machine according to  claim 1 , further comprising an outlet duct connected to the recirculation pump outlet and the bifurcation in the outlet duct. 
     
     
         5 . The washing machine according to  claim 1 , wherein the recirculation pump outlet is located at a body portion of the recirculation pump and the bifurcation is located in the body portion of the recirculation pump. 
     
     
         6 . The washing machine according to  claim 1 , further comprising a treatment agents dispenser configured to supply one or more treating agents into the washing tub. 
     
     
         7 . The washing machine according to  claim 1 , wherein the first region is a bottom part of the washing tub. 
     
     
         8 . The washing machine according to  claim 1 , wherein the second region is an upper part of the washing tub. 
     
     
         9 . The washing machine according to  claim 1 , wherein the first duct defines a first volume and the second duct defines a second volume, wherein the first volume is lower than the second volume. 
     
     
         10 . A method for operating a laundry washing machine comprising:
 a washing drum configured to receive laundry to be washed;   a washing tub external to a washing drum;   a water supply system configured to convey water to the washing tub;   a recirculation system configured to drain a liquid from the bottom of the washing tub and to re-admit the liquid into a first region and a second region of the washing tub, the recirculation system comprising:   a first duct terminating at the first region wherein the liquid may circulate to reach the washing tub;   a second duct terminating at the second region wherein the liquid may circulate to reach the washing tub;   a recirculation pump having an inlet connected to the bottom of the washing tub and an outlet configured to convey the liquid to a bifurcation leading to the first duct and the second duct;   wherein the first duct and the second duct are configured so that the liquid in the first duct requires a first pressure to reach the washing tub which is lower than a second pressure required for the liquid in the second duct to reach the washing tub; wherein the method comprises:   operating the recirculation pump in a first functioning condition to circulate liquid only in the first duct to reach the washing tub; and   operating the recirculation pump in a second functioning condition to circulate liquid both in the first duct and the second duct to reach the washing tub.   
     
     
         11 . The method according to  claim 10 , wherein the second functioning condition comprises driving the recirculation pump at a higher power than in the first functioning condition. 
     
     
         12 . The method according to  claim 10 , wherein the recirculation pump comprises a variable-speed pump, wherein the first functioning condition comprises driving the recirculation pump at a first speed, and the second functioning condition comprises driving the recirculation pump at a second speed, the second speed being higher than the first speed. 
     
     
         13 . The method according to  claim 10 , wherein operating the recirculation pump in the first functioning condition or the second functioning condition comprises driving the recirculation pump with a pulsed waveform. 
     
     
         14 . The method according to  claim 13 , wherein the first functioning condition comprises driving the recirculation pump so that its speed has a first pulsed waveform having a first duty cycle, and the second functioning condition comprises driving the recirculation pump so that its speed has a second pulsed waveform having a second duty cycle, the second duty cycle being higher than the first duty cycle. 
     
     
         15 . The method according to  claim 10 , wherein the recirculation pump comprises a variable-speed pump, and wherein in the first functioning condition comprises driving the recirculation pump so that its speed has a first pulsed waveform having a first average speed and in the second functioning condition comprises driving the recirculation pump so that its speed has a second pulsed waveform having a second average speed, the second average speed being higher than the first average speed.