Home laundry dryer

Abstract

A laundry dryer ( 1 ) includes a closed-circuit, hot-air generator ( 5 ). The hot-air generator ( 5 ) is provided with a heat-pump assembly ( 11 ). The heat-pump assembly ( 11 ) in turn includes an evaporator ( 13 ) and a condenser ( 14 ). Refrigerant vapor-quality adjusting means ( 17 ) is structured for adjusting, at the refrigerant-outlet of the evaporator ( 13 ), the ratio between the amount of refrigerant in gaseous state and the whole amount of refrigerant. Detecting means are able to measure the current value of at least one physical quantity of the laundry dryer ( 1 ). An auxiliary refrigerant/refrigerant heat exchanger ( 18 ) is crossed, at the same time, by the high-pressure refrigerant directed towards the refrigerant expansion device ( 16 ), and by the low-pressure refrigerant coming out of the refrigerant-outlet of the evaporator ( 13 ), and is structured for transferring heat from the high-pressure refrigerant to the low-pressure refrigerant so to heat up the low pressure refrigerant.

1 . A laundry dryer comprising an outer boxlike casing structured for resting on the floor and, inside the casing, a laundry container structured for housing the laundry to be dried, and a closed-circuit, hot-air generator structured to circulate, through the laundry container, a stream of hot air;
 the hot-air generator in turn comprising: an air recirculating conduit having its two ends connected to the laundry container; air circulating means structured to produce, inside the air recirculating conduit, an airflow which flows through said laundry container; and a heat-pump assembly structured to cool the airflow coming out from the laundry container for condensing the moisture in said airflow, and then to heat the airflow returning back into the laundry container;   said heat-pump assembly comprising:
 a first air/refrigerant heat exchanger which is located along the air recirculating conduit, and is structured for transferring heat from the airflow arriving from the laundry container to the refrigerant so as to condense the moisture in the airflow; 
 a second air/refrigerant heat exchanger which is located along the air recirculating conduit, downstream of the first heat exchanger, and is structured for transferring heat from the refrigerant to the airflow directed back into the laundry container so as to heat said airflow; 
 a refrigerant compressing device which is interposed between a refrigerant-outlet of the first heat exchanger and a refrigerant-inlet of the second heat exchanger, and it is structured for compressing the refrigerant directed towards the second heat exchanger so that refrigerant pressure and temperature are much higher at the refrigerant-inlet of the second heat exchanger than at the refrigerant-outlet of the first heat exchanger; and 
 a refrigerant expansion device which is interposed between the refrigerant-outlet of the second heat exchanger and the refrigerant-inlet of the first heat exchanger, and is structured so as to produce an expansion of the refrigerant; 
   wherein, said heat-pump assembly additionally comprises:
 an auxiliary refrigerant/refrigerant heat exchanger comprising a high-pressure side and a low-pressure side, and which is structured so that the high- and low-pressure sides are thermically coupled to one another so to allow heat transfer from the high-pressure and high-temperature refrigerant to the low-pressure and low-temperature refrigerant; 
 refrigerant vapor-quality adjusting means structured for adjusting the ratio, at the refrigerant-outlet of the first heat exchanger, between the amount of refrigerant in a gaseous state and the whole amount of refrigerant; 
 detecting means able to measure the current value of at least one physical quantity associated with the heat-pump assembly and/or to the airflow; and 
 a central control unit structured for controlling said refrigerant vapor-quality adjusting means according to the time-progression of said at least one physical quantity. 
   
     
     
         2 . A laundry dryer according to  claim 1 , wherein said at least one physical quantity is the temperature and/or pressure of the refrigerant at the refrigerant-inlet or at the refrigerant-outlet of said first air/refrigerant heat exchanger; and/or the temperature rise or drop of the refrigerant flowing through said first air/refrigerant heat exchanger. 
     
     
         3 . A laundry dryer according to  claim 1 , wherein said at least one physical quantity is the temperature and/or pressure of the refrigerant at a low-pressure refrigerant inlet or at a low-pressure refrigerant outlet of the low-pressure side of said refrigerant/refrigerant heat exchanger; and/or the temperature and/or pressure of the refrigerant at a high-pressure refrigerant inlet or at a high-pressure refrigerant outlet of the high-pressure side of said refrigerant/refrigerant heat exchanger; and/or the temperature rise of the refrigerant flowing through the low-pressure side of said refrigerant/refrigerant heat exchanger; and/or the temperature drop of the refrigerant flowing through the high-pressure side of said refrigerant/refrigerant heat exchanger. 
     
     
         4 . A laundry dryer according to  claim 1 , wherein said at least one physical quantity is the temperature and/or pressure of the refrigerant at a suction and/or at a delivery of said refrigerant compressing device. 
     
     
         5 . A laundry dryer according to  claim 1 , wherein said at least one physical quantity is the temperature and/or pressure of the refrigerant at the refrigerant inlet or at the refrigerant outlet of said second air/refrigerant heat exchanger. 
     
     
         6 . A laundry dryer according to  claim 1 , wherein said at least one physical quantity is the temperature and/or moisture degree of the airflow entering into, or coming out of, said laundry container. 
     
     
         7 . A laundry dryer according to  claim 1 , wherein the central control unit is structured for controlling said refrigerant vapor-quality adjusting means so as to selectively keep said ratio below or equal to 1. 
     
     
         8 . A laundry dryer according to  claim 7 , characterized in that the central control unit is structured for controlling said refrigerant vapor-quality adjusting means so as to maintain between 0.80 and 0.99 the ratio, at the refrigerant-outlet of said first heat exchanger, between the amount of refrigerant in the gaseous state and the whole amount of refrigerant. 
     
     
         9 . A laundry dryer according to  claim 1 , wherein the refrigerant vapor-quality adjusting means comprise high-pressure refrigerant cooling means which are structured for selectively cooling down the high-pressure refrigerant flowing from the second heat exchanger to the refrigerant expansion device. 
     
     
         10 . A laundry dryer according to  claim 9 , wherein said high-pressure refrigerant cooling means comprise a third air/refrigerant heat exchanger which is connected in series to the second air/refrigerant heat exchanger. 
     
     
         11 . A laundry dryer according to  claim 10 , wherein said high-pressure refrigerant cooling means additionally comprise an auxiliary ventilation device which is structured for channeling a stream of cooling air towards the body of said third air/refrigerant heat exchanger. 
     
     
         12 . A laundry dryer according to  claim 1 , wherein the refrigerant vapor-quality adjusting means comprise refrigerant flow-rate adjusting means which are structured for varying the flow-rate of the low-pressure refrigerant flowing through the first air/refrigerant heat exchanger. 
     
     
         13 . A laundry dryer according to  claim 12 , wherein said refrigerant flow-rate adjusting means comprise a variable speed refrigerant compressing device, or an electrically-operated refrigerant expansion valve, or an electrically-operated multiple capillary-tube expansion system. 
     
     
         14 . A laundry dryer according to  claim 3 , wherein said detecting means comprise sensor means structured for detecting the temperature and/or pressure of the refrigerant at the low-pressure refrigerant inlet of said refrigerant/refrigerant heat exchanger, and/or at the low-pressure refrigerant outlet of said refrigerant/refrigerant heat exchanger, and/or at the high-pressure refrigerant inlet of said refrigerant/refrigerant heat exchanger, and/or at the high-pressure refrigerant outlet of said refrigerant/refrigerant heat exchanger. 
     
     
         15 . An operating method of a laundry dryer comprising an outer boxlike casing structured for resting on the floor and, inside the casing, a laundry container structured for housing the laundry to be dried, and a closed-circuit, hot-air generator structured to circulate through the laundry container a stream of hot air; the hot-air generator being provided with a heat-pump assembly structured to cool the airflow coming out from the laundry container for condensing the moisture in said airflow, and then to heat the airflow returning back into the laundry container;
 said heat-pump assembly comprising: a first air/refrigerant heat exchanger ( 13 ) which is structured for transferring heat from the airflow arriving from the laundry container to a low-pressure refrigerant so as to condense the moisture in the airflow; a second air/refrigerant heat exchanger which is structured for transferring heat from a high-pressure refrigerant to the airflow directed back into the laundry container so as to heat said airflow; the operating method comprising the steps of:
 measuring the current value of at least one physical quantity associated with the heat-pump assembly and/or the airflow, 
 on the basis of the time-progression of said at least one physical quantity, controlling refrigerant vapor-quality adjusting means structured for adjusting, at a refrigerant-outlet of the first heat exchanger, the ratio between the amount of refrigerant in a gaseous state and the whole amount of refrigerant. 
 feeding the refrigerant to a high pressure side and to a low pressure side of an auxiliary refrigerant/refrigerant heat exchanger for transferring heat from the high-pressure and high-temperature refrigerant flowing through high pressure side to the low-pressure and low-temperature refrigerant flowing through the low pressure side. 
   
     
     
         16 . A laundry-dryer operating method according to  claim 15 , wherein the refrigerant vapor-quality adjusting means are controlled so as to selectively maintain below or equal to 1 the ratio between the amount of refrigerant in the gaseous state and the whole amount of refrigerant. 
     
     
         17 . A laundry-dryer operating method according to  claim 16 , wherein said refrigerant vapor-quality adjusting means are controlled so as to selectively maintain between 0.80 and 0.99 the ratio, at the refrigerant-outlet of said first heat exchanger, between the amount of refrigerant in the gaseous state and the whole amount of refrigerant. 
     
     
         18 . A laundry-dryer operating method according to  claim 15 , wherein said at least one physical quantity is the temperature and/or pressure of the refrigerant at a refrigerant-inlet or at the refrigerant-outlet of said first air/refrigerant heat exchanger; and/or the temperature rise or drop of the refrigerant flowing through said first air/refrigerant heat exchanger. 
     
     
         19 . A laundry-dryer operating method according to  claim 15 , wherein said at least one physical quantity is the temperature and/or pressure of the refrigerant at a low-pressure refrigerant inlet or at a low-pressure refrigerant outlet of the low-pressure side of said refrigerant/refrigerant heat exchanger; and/or the temperature and/or pressure of the refrigerant at a high-pressure refrigerant inlet or at a high-pressure refrigerant outlet of the high-pressure side of said refrigerant/refrigerant heat exchanger; and/or the temperature rise of the refrigerant flowing through the low-pressure side of said refrigerant/refrigerant heat exchanger; and/or the temperature drop of the refrigerant flowing through the high-pressure side of said refrigerant/refrigerant heat exchanger. 
     
     
         20 . A laundry-dryer operating method according to  claim 15 , wherein said at least one physical quantity is the temperature and/or pressure of the refrigerant at a suction and/or at a delivery of said refrigerant compressing device. 
     
     
         21 - 44 . (canceled)