Laundry drying apparatus with heater unit having adjustable temperature thresholds

Patent metadata

Field	Value
Publication number	US-10184208-B2
Application number	US-201515328796-A
Country	US
Kind code	B2
Filing date	Jul 7, 2015
Priority date	Jul 25, 2014
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

A laundry drying apparatus, in particular dryer or washing machine having drying function, has: a cabinet, a control unit ( 4 ) adapted to control a laundry drying cycle according to at least one drying program, a drum ( 18 ) rotatably arranged within the cabinet for receiving laundry to be dried, a drying air channel ( 20 ) adapted at least to guide drying air into the drum ( 18 ), and a heater unit ( 6 ) arranged at or in the drying air channel ( 20 ) and being adapted to heat the drying air. The heater unit ( 6 ) has two or more heating levels. A temperature sensor unit is adapted to detect the temperature of the drying air and to provide at least one temperature signal to the control unit ( 4 ). The control unit ( 4 ) is adapted to control the heater unit ( 6 ) to heat the drying air at a selected one of the two or more heating levels. The control unit ( 4 ) is adapted to select or determine and apply during the drying cycle one of two or more temperature threshold sets, wherein the two or more temperature threshold sets are used by the control unit ( 4 ) for determining the heating level to be applied by the heater unit ( 6 ) in dependency of the at least one temperature signal from the temperature sensor unit. The control unit ( 4 ) is adapted to select or determine one of the two or more temperature threshold sets in dependency of one or more operating parameters of the apparatus, wherein the temperature thresholds of the temperature threshold sets are mutually different or are not identical. During execution of the laundry drying cycle the control unit ( 4 ) is adapted to select or determine one of the two or more temperature threshold sets in dependency of one or more of the following operation parameters:
a) the time or temporal progress of the laundry drying cycle, b) one or more operation parameters of or for the heater unit ( 6 ), c) an electrical or mechanical parameter of the drum ( 18 ) motor, d) a temporal gradient of the drying air temperature during execution of the laundry drying cycle, and e) an ambient temperature indicative for the temperature outside the apparatus cabinet or a temperature indicative of an apparatus component temperature.

First claim

The invention claimed is:

1. Laundry drying apparatus, in particular dryer or washing machine having drying function, comprising:
a cabinet,
a control unit adapted to control a laundry drying cycle according to at least one drying program,
a drum rotatably arranged within the cabinet for receiving laundry to be dried,
a drying air channel adapted at least to guide drying air into the drum,
a heater unit arranged at or in the drying air channel and being adapted to heat the drying air, wherein the heater unit has two or more heating levels, and
a temperature sensor unit adapted to detect the temperature of the drying air and to provide at least one temperature signal to the control unit,
wherein the control unit is adapted to control the heater unit to heat the drying air at a selected one of the two or more heating levels,
wherein the control unit is adapted to select or determine and apply during the drying cycle one of two or more temperature threshold sets (T MIN1 . . . 3 , T MAX1 . . . 3 ), wherein the two or more temperature threshold sets are used by the control unit for determining the heating level to be applied by the heater unit in dependency of the at least one temperature signal from the temperature sensor unit,
wherein the control unit is adapted to select or determine one of the two or more temperature threshold sets (T MIN1 . . . 3 /T MAX1 . . . 3 ) in dependency of one or more operating parameters (t OFF _ ON , Δ ON _ OFF , E OFF _ ON ) of the apparatus, and
wherein the temperature thresholds of the temperature threshold sets (T MIN1 . . . 3 /T MAX1 . . . 3 ) are mutually different or are not identical,
wherein during execution of the laundry drying cycle the control unit is adapted to select or determine one of the two or more temperature threshold sets (T MIN1 . . . 3 /T MAX1 . . . 3 ) in dependency of one or more of the following operation parameters:
a) the time or temporal progress of the laundry drying cycle,
b) one or more operation parameters of or for the heater unit,
c) an electrical or mechanical parameter of the drum motor,
d) a temporal gradient of the drying air temperature during execution of the laundry drying cycle, and
e) an ambient temperature indicative for the temperature outside the apparatus cabinet or a temperature indicative of an apparatus component temperature.

2. Laundry drying apparatus according to claim 1 , wherein the b) one or more operation parameters of the heater unit include one or more of:
the number of times (n_OFF) the control unit reduces the heating level of the heater unit or the number of times (n_ON) the control unit increases the heating level of the heater unit or the number of periods in which the control unit controls a reduction and increase of the heating level of the heater unit,
the time or duration of a period (t ON _ OFF ) in which the control unit increases the heating level of the heater unit to the subsequent reduction of the heating level,
the time or duration of a period (t OFF _ ON ) in which the control unit decreases the heating level of the heater unit to the subsequent increase of the heating level,
the time or duration of a period in which the control unit controls a reduction and the subsequent increase of the heating level of the heater unit,
the heating energy supplied to the heater unit during a period in which the control unit controls a reduction and the subsequent increase of the heating level of the heater unit, and
the power supplied to the heater unit averaged over predetermined time periods.

3. Laundry drying apparatus according to claim 1 , wherein the c) electrical or mechanical parameter of the drum motor is one or more of:
the motor current,
the phase voltage,
the consumed motor power,
the phase of the voltage applied to the motor, and
the torque generated by the motor.

4. Laundry drying apparatus according to claim 1 , wherein the temporal gradient of the drying air temperature is determined using the one or more signals of the temperature sensor unit.

5. Laundry drying apparatus according to claim 1 ,
wherein the heater unit has at least three heating levels comprising a non-heating level and a first and a second heating level, wherein the heating power at the first and second heating level is above 0 W and wherein the heating power of the second heating level is higher than the heating power of the first heating level, or
wherein the heater unit is an electrical resistivity heater unit having at least two resistivity heater elements wherein a first heating level with a first heating power is provided by powering a first one of the resistivity heater elements and a second heating level with a second heating power is provided by powering a second one of the resistivity heater elements or the first and second resistivity heater elements.

6. Laundry drying apparatus according to claim 1 , wherein the laundry drying apparatus is a condensate-type drying apparatus having a closed drying air loop comprising the drying air channel and the drum as a portion of the drying air loop, and wherein a condensation unit is arranged in the drying air channel upstream the heater unit.

7. Laundry drying apparatus according to claim 1 , wherein for controlling the heater unit the temperature sensor unit comprises at least one temperature sensor ( 10 a - c ) arranged to detect the drying air temperature at one or more of the following positions:
downstream the heater unit and upstream the drum air inlet,
downstream the drum air outlet,
within a tub surrounding the drum, and
at the drum.

8. Laundry drying apparatus according to claim 1 , wherein the control unit determining or selecting of the one of the two or more temperature threshold sets (T MIN1 . . . 3 /T MAX1 . . . 3 ) in dependency of one or more operating parameters of the apparatus comprises:
a storing element of the control unit stores at least two different predetermined temperature threshold sets (T MIN1 . . . 3 /T MAX1 . . . 3 ) and the control unit is adapted to select one of these predetermined temperature threshold sets (T MIN1 . . . 3 /T MAX1 . . . 3 ) in dependency of the one or more operating parameters,
a storing element of the control unit stores at least three different predetermined temperature thresholds and, in dependency of the one or more operating parameters, the control unit is adapted to select one of these predetermined temperature thresholds as the first lower temperature threshold (T MIN1 . . . 3 ) and one as the second higher temperature threshold (T MAX1 . . . 3 ), or
the control unit is adapted to determine one of the two or more temperature threshold sets (T MIN1 . . . 3 /T MAX1 . . . 3 ) by calculating at least one of the temperature thresholds for the next predetermined temperature threshold set to be applied on the basis of the one or more operating parameters.

9. Laundry drying apparatus according to claim 1 , wherein each one of the temperature threshold set (T MIN1 . . . 3 /T MAX1 . . . 3 ) comprises
a first higher temperature threshold (T MAX1 . . . 3 ) used by the control unit for determining a drying air temperature state at which the heating power of the heater unit has to be set to a lower heating power, and
a second lower temperature threshold (T MIN1 . . . 3 ) used by the control unit for determining a drying air temperature state at which the heating power of the heater unit has to be set to a higher heating power.

10. Laundry drying apparatus according to claim 1 , wherein during execution of the laundry drying cycle the control unit is adapted to select the one of the two or more temperature threshold sets (T MIN1 . . . 3 /T MAX1 . . . 3 ) independent of a detected la

Assignees

• Electrolux Appliances AB

Inventors

• Rizzi Marco
• Girotto Terenzio

Classifications

• D06F2105/28

  Electric heating · CPC title

• D06F2103/08

  Humidity · CPC title

• D06F58/28 Primary

  Textiles & Paper · mapped topic

• D06F58/02

  having dryer drums rotating about a horizontal axis · CPC title

• D06F2058/2829

  Textiles & Paper · mapped topic