Method of Operating a Washing Machine and Washing Machine

Abstract

A washing machine ( 1 ), is operable in a recirculation washing mode, wherein a filter clogging state of a washing liquid filter ( 13 ) of a recirculation unit is monitored. If a critical filter clogging state is detected, the recirculation washing mode is deactivated and substituted by a non-recirculation washing mode.

1 . A method of operating a washing machine operable in a recirculation washing mode, wherein a filter clogging state of a washing liquid filter of a recirculation unit is monitored, and if a critical filter clogging state is detected, the recirculation washing mode is deactivated and substituted by a non-recirculation washing mode. 
     
     
         2 . A method according to  claim 1 , wherein the substitution of the recirculation washing mode by the non-recirculation mode involves increasing, with respect to the recirculation mode, a filling level of washing liquid in a tub of the washing machine. 
     
     
         3 . A method according to  claim 2 , wherein increasing the filling level during operation of the washing machine involves feeding additional liquid to the tub. 
     
     
         4 . A method according to  claim 1 , wherein monitoring the filter clogging state involves at least one of measuring a washing liquid flow of washing liquid in a recirculation circuit, and/or measuring a washing liquid pressure and/or pressure change in the tub effected by recirculation washing operation and/or optically detecting at least one particular feature of the washing liquid filter, and wherein the recirculation mode is deactivated and substituted if at least one of the measured washing liquid flow, and/or measured washing liquid pressure and/or pressure change and/or optically detected particular feature is indicative of a critical filter clogging state. 
     
     
         5 . A method according to  claim 4 , wherein at least one of the measured washing liquid flow, and/or washing liquid pressure and/or pressure change is compared to a reference flow value, and/or reference pressure value and/or reference pressure change value, respectively, and a critical clogging state is determined to exist if at least one of the washing liquid flow is less than or equal the reference flow value, and/or the washing liquid pressure is higher than or equal the reference pressure value and/or the washing liquid pressure change is less than or equal the reference pressure change value. 
     
     
         6 . A method according to  claim 1 , wherein upon deactivating the recirculation mode during operation of the washing machine, a conduit connecting a bottom section of the tub of the washing machine to a recirculation unit is closed via a valve. 
     
     
         7 . A method according to  claim 1 , wherein notification of at least one of an event of deactivation of the recirculation mode and occurrence of a critical filter clogging state is made available to a user. 
     
     
         8 . A washing machine operable in a recirculation washing mode, comprising a tub, a recirculation unit for recirculating washing liquid in a recirculation circuit provided with the tub, and at least one recirculation washing liquid filter, and further comprising an electronic control unit adapted to operate the washing machine according to  claim 1 . 
     
     
         9 . A washing machine according to  claim 8 , the recirculation unit comprising a pump for pumping washing liquid in a recirculation circuit, wherein said at least one recirculation washing liquid filter is provided in the recirculation circuit and arranged upstream of the pump, the recirculation washing liquid filter being adapted to retain lint, loose fibers, dirt particles, impurities and foreign matter from entering the pump. 
     
     
         10 . A washing machine according to at  claim 8 , further comprising at least one of a flow meter for measuring a washing liquid flow in the recirculation circuit, and/or a pressure sensor for measuring a washing liquid pressure or pressure change in the tub and/or an optical sensor for optically detecting at least one particular feature of the recirculation washing liquid filter, respectively connected to the electronic control unit in such a way that the measured washing liquid flow, and/or measured washing liquid pressure and/or pressure change and/or optically detected particular feature are available for operating the washing machine accordingly. 
     
     
         11 . A washing machine according to  claim 9 , wherein in a conduit connecting an opening provided in a bottom section of the tub with an input side of the pump there is provided a valve arranged and adapted to open and close the conduit. 
     
     
         12 . A washing machine according to  claim 8 , further comprising a user messaging or information unit adapted to visually and/or audibly indicate to a user an event of deactivation of the recirculation mode and/or the occurrence of a critical clogging state. 
     
     
         13 . A washing machine according to  claim 8 , comprising an integral filter unit having a recirculation filter section and draining filter section, wherein at least said recirculation washing liquid filter is accommodated in the recirculation filter section. 
     
     
         14 . A washing machine according to  claim 8 , wherein the pump is operable as a recirculation pump and as a draining pump, and wherein a valve, preferably a three way valve, is provided for connecting the pump either to the recirculation circuit or a draining circuit. 
     
     
         15 . A washing machine according to  claim 8 , further comprising a liquid inlet adapted for feeding additional or fresh liquid to the tub and cooperating with the electronic control unit such that in the event of deactivation of the recirculation washing mode due to a critical clogging state of the recirculation washing liquid filter, additional or fresh liquid is fed to the tub. 
     
     
         16 . A washing machine according to  claim 9 , further comprising at least one of a flow meter for measuring a washing liquid flow in the recirculation circuit, and/or a pressure sensor for measuring a washing liquid pressure or pressure change in the tub and/or an optical sensor for optically detecting at least one particular feature of the recirculation washing liquid filter, respectively connected to the electronic control unit in such a way that the measured washing liquid flow, and/or measured washing liquid pressure and/or pressure change and/or optically detected particular feature are available for operating the washing machine accordingly. 
     
     
         17 . A washing machine according to  claim 10 , further comprising a user messaging or information unit adapted to visually and/or audibly indicate to a user an event of deactivation of the recirculation mode and/or the occurrence of a critical clogging state.