EP3111002A1

EP3111002A1 - Laundry dryer with a cloth disentangling mode and method for controlling the same

Info

Publication number: EP3111002A1
Application number: EP14707397.7A
Authority: EP
Inventors: Selcuk KARAGOZ; Bora Abdik; Onur ERCAN
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2014-02-28
Filing date: 2014-02-28
Publication date: 2017-01-04
Also published as: WO2015127995A1

Abstract

The present invention relates to a method for controlling a laundry dryer (1) in which the clothes are dried by conveying heated process air through the drum (2). The method of the present invention comprises a step (S1a-S1d, S3a-S3d) of monitoring a rate of change in the relative humidity ΔRH/Δt of the process air and a step (S2) of interrupting a normal drying mode and initiating a disentangling mode if it is judged that the clothes are entangled based on a monitoring result.

Description

LAUNDRY DRYER WITH A CLOTH DISENTANGLING MODE AND METHOD FOR CONTROLLING THE SAME

The present invention relates to a laundry dryer, in particular a domestic laundry dryer in which the clothes are dried by conveying heated process air through a laundry drum. The present invention more particularly relates to a laundry dryer which senses entanglement of the clothes inside the drum and to a method for controlling such a laundry dryer.
Several techniques have been devised for drying wet laundry. In particular, ventless laundry dryers such as heat-pump type laundry dryers and condenser type laundry dryers are well known in the art. The heat-pump technology constitutes a relatively energy-efficient method of drying laundry. The heat pump type laundry dryer typically consists of a process air circuit and a refrigerant circuit which are arranged so as to mutually exchange heat. The process air circuit includes a duct for circulating process air through a laundry drum by means of a fan. The refrigerant circuit includes an evaporator, a compressor, a condenser, and an expansion valve such as a capillary in serial connection for circulating a refrigerant. The evaporator and the condenser are particularly arranged in heat exchange with the process air within the circulation duct for respectively dehumidifying and subsequently heating the process air. As the process air which is heated by the condenser strikes the clothes inside the drum, the heat of the process air is partly transferred to the wet clothes, and, in turn, the humidity in the clothes diffuses into the process air and is subsequently drawn out of the drum into the duct. The heat in the humid process air is absorbed by the evaporator. Thereby, the process air is dehumidified by condensation. The heat absorbed by the evaporator is subsequently partly transferred back to the process air by means of the condenser. Thereby, a drying performance of the laundry dryer is increased.
A problem with the drying process is that the clothes inside the drum may get from time to time entangled as they are aerated by rotation. Several factors influence the entanglement of the clothes. Such factors include a type and size of the clothes, a distribution of the clothes inside the drum, and a shape of the drum paddles or the like.
The drying performance of the laundry dryer degrades when the clothes get entangled. In particular, the total running time of the drying program prolongs, the energy consumption increases. Moreover, despite of the prolongation, there is a risk that the clothes may still remain partly wet when the drying program is terminated.
WO 2012/120851 A1 discloses a clothes dryer comprising electrodes which are arranged to contact the clothes inside the rotating drum. In this clothes dryer, the resistance values across the electrodes are measured and utilized to determine whether the clothes inside the drum are entangled.
An objective of the present invention is to provide a laundry dryer and a method of controlling the laundry dryer which overcomes the aforementioned drawbacks of the prior art and which enables a quick and reliable detection of entanglement of the clothes, and which also initiates effective countermeasures for disentangling the clothes.
This objective has been achieved by the method according to the present invention as defined in claim 1, and the laundry dryer according to the present invention as defined in claim 7. Further achievements have been attained by the subject-matters respectively defined in the dependent claims.
The control method of the present invention comprises a step of monitoring a rate of change in the relative humidity of the process air and a step of interrupting a drying mode and initiating a disentangling mode if it is judged that the clothes are entangled based on a monitoring result.
In an embodiment, it is judged that the clothes are entangled if a rate of change in the relative humidity is greater than a threshold rate of change in the relative humidity.
In another embodiment, if it is judged that the clothes have been disentangled based on the monitoring result, the disentangling mode is terminated and the drying mode is resumed.
In another embodiment, it is judged that the clothes are disentangled if the rate of change in the relative humidity is smaller than the threshold rate of change in the relative humidity.
In another embodiment, in the disentanglement mode one or more than one countermeasures are sequentially initiated to disentangle the clothes. In particular, in the disentangling mode one or more than one of the following actions are performed in a predetermined sequence in order to disentangle the clothes: stopping the motor, reversing rotation direction of the motor, rotating the motor at an irregular speed and irregularly accelerating/decelerating the motor.
In an alternative embodiment, if the clothes cannot be successfully disentangled during the disentangling mode even after elapse of a predetermined time, then the disentangling mode is forcedly terminated and the user is audibly and/or visually informed via the user interface and prompted to disentangle the clothes manually. In this embodiment, the drying mode is resumed after the user has disentangled the clothes manually. This is checked by way of detecting opening/closing of the door and/or an elapse of a predetermined duration, or a user confirmation to be input via the user interface. Thereafter, the drying mode is resumed.
In another embodiment, if it is judged that the clothes are entangled based on a monitoring result, then it is dispensed with initiating the disentangling mode on condition that the disentangling mode has already been initiated and terminated for more than a predetermined number of times. In this embodiment, the user is informed similarly as before via the interface about the judgment that the clothes are entangled and prompted to disentangle the clothes manually. Thus, the disentangling mode is subsequently not initiated. In this embodiment, the drying mode is resumed after the user has disentangled the clothes manually. This is checked similarly as before by way of detecting opening/closing of the door and/or an elapse of a predetermined duration, or a user confirmation to be input via the user interface. Thereafter, the drying mode is resumed.
The method of the present invention can be applied to a laundry dryer of a heat-pump type, a condenser type, or a vented type. Thus, the method of the present invention is not limited to a particular technology.
By the present invention, a laundry dryer has been provided that enables quick and reliable sensing of entanglement of clothes. In case of sensing an entanglement, the laundry dryer initiates countermeasures to disentangle the clothes by applying a different rotation regime to the motor and resumes the drying mode upon detection of successful disentanglement. However, in case of a forced termination of the disentangling mode or after several repetitions of the entangling mode, a user is audibly and/or visually informed about the entanglement and prompted to manually disentangle the clothes. Thereby, a disentanglement management of the clothes has been improved. In particular, the drying process has been prevented from prolonging and the energy efficiency of the laundry dryer has been enhanced.
Additional advantages of the method of the present invention and the laundry dryer of the present invention will become apparent with the detailed description of the embodiments with reference to the accompanying drawings in which:
Figure 1 – is a schematic view of a laundry dryer according to an embodiment of the present invention;
Figure 2 – is a flowchart showing a method for controlling the laundry dryer according to an embodiment of the present invention.
The reference signs appearing on the drawings relate to the following technical features.

Laundry dryer
Drum
Process air circuit

3a. Duct
3b. Fan
4. Control unit
5. User interface
6. Sensor unit
7. Refrigeration circuit
7a. Evaporator
7b. Compressor
7c. Condenser
7d. Capillary
The laundry dryer (1) comprises a drum (2) for receiving clothes to be dried, a motor (not shown) for rotating the drum (2) and a process air circuit (3) for conveying heated process air through the drum (2) in order to dry the clothes (Fig. 1).
The laundry dryer (1) of the present invention comprises a control unit (4) for controlling the motor and the process air circuit (3), wherein the control unit (4) has a normal drying mode for drying the clothes and a disentangling mode for disentangling the entangled clothes, a user interface (5) for receiving user inputs and outputting information and a sensor unit (6) adapted to measure relative humidity of the process air and to output a signal to the control unit (4), the signal being indicative of the measured relative humidity (Fig. 1).
The control method of the present invention comprises a step (S1a-S1d, S3a-S3d) of monitoring a rate of change in the relative humidity ΔRH/Δt of the process air and a step (S2) of interrupting the drying mode and initiating the disentangling mode if it is judged that the clothes are entangled based on a monitoring result (Fig. 2).
Herein t designates time (seconds) and RH designates the relative humidity (%) of the process air. Δ designates a corresponding change in these quantities. In the laundry dryer (1), when the clothes get entangled, the heated process air cannot sufficiently penetrate into the clothes. Consequently, diffusion of the humidity into the process air is reduced. Such a reduction can be observed as a sudden drop in the temporal evolution of the relative humidity of the process air. In the present invention such drops are monitored to detect entanglement of the clothes. Since relative humidity also depends on the temperature, the reliability of detecting an entanglement is considerably increased by way of monitoring the relative humidity of the process air. Several techniques are available for measuring relative humidity RH. In an embodiment the sensor unit (6) utilizes a wet bulb thermometer (not shown) and a dry bulb thermometer (not shown).
In another embodiment, the method comprises a step (S4) of terminating the disentangling mode and resuming the drying mode if it is judged that the clothes have been disentangled based on the monitoring result (Fig. 2).
In an alternative embodiment (not shown), the method comprises a step of forcedly terminating the disentangling mode when the clothes have not been disentangled even after elapse of a predetermined time and a step of informing the user audibly and/or visually via the user interface (5) about the entanglement of the clothes and prompting the user to disentangle the clothes manually. In this embodiment, the drying mode is resumed after the user has disentangled the clothes manually. This is checked by way of detecting of opening/closing of the door and/or an elapse of a predetermined duration, or a user confirmation to be input via the user interface (5). Thereafter, the drying mode is resumed.
In another embodiment, the monitoring step (S1a-S1d, S3a-S3d) includes a step (S1a, S3a) of measuring the relative humidity of the process air, a step (S1b, S3b) of calculating a rate of change in the relative humidity based on the measured relative humidity, a step (S1c, S3c) of comparing the calculated rate of change in the relative humidity with a threshold rate of change in the relative humidity, a step (S1d, S3d) of determining whether the clothes are entangled/disentangled based on the comparison result. In this embodiment, it is judged that the clothes are entangled if the calculated rate of change in the relative humidity is greater than the threshold rate of change in the relative humidity, and it is judged that the clothes are disentangled if the calculated rate of change in the relative humidity is smaller than the threshold rate of change in the relative humidity (Fig. 2). Herein the threshold rate of change in the relative humidity is designated by TH. The control unit (4) has a memory means (not shown) for storing the measured relative humidity values. The control unit (4) also has a micro processing means (not shown) for performing arithmetic and logical operations.
In another embodiment, in the disentangling mode one or more than one of the following actions are performed in a predetermined sequence in order to disentangle the clothes: a step of stopping the motor, a step of reversing rotation direction of the motor, a step of rotating the motor at an irregular speed and a step of irregularly accelerating/decelerating the motor. The term irregular should be conceived in the sense that it designates settings which are different than those settings which are normally applied in the drying mode. The control unit (4) has a memory means for storing the settings for the above-mentioned actions.
In another embodiment (not shown), the method comprises a step of dispensing with initiating the disentangling mode when it is judged that the clothes are entangled based on a monitoring result if the disentangling mode has already been initiated and terminated for more than a predetermined number of times. In this embodiment, the method further comprises a step of informing a user via the interface (5) about the judgment that the clothes are entangled and prompting the user to disentangle the clothes manually. Thus, the disentangling mode is subsequently not initiated. In this embodiment, said predetermined number is not limited to a specific number of entanglement events previously encountered throughout the same drying course. In a version of this embodiment, the user is informed when it is judged that the clothes are entangled for the second time. In another version of this embodiment, the user is enabled to set said predetermined number via the user interface (5). In this embodiment, the method further comprises a step of resuming the drying mode after the user has disentangled the clothes manually. This is checked by way of detecting of opening/closing of the door and/or an elapse of a predetermined duration, or a user confirmation to be input via the user interface (5). Thereafter, the drying mode is resumed.
The laundry dryer (1) to which the method of the present invention has been applied is not limited to a particular technology. Thus, the method of the present invention can be applied to a laundry dryer (1) of a heat-pump type, a condenser type, or a vented type.
In another embodiment, the laundry dryer (1) is a heat-pump type laundry dryer (1) (Fig. 1). In this embodiment, the process air circuit (3) comprises a duct (3a) which is arranged to discharge the process air into the drum (2) and to draw the process air out of the drum (2) and a fan (3b) which is arranged to circulate the process air in the duct (3a) through the drum (2). In this embodiment, the laundry dryer (1) further comprises a refrigerant circuit (7) which includes an evaporator (7a), a compressor (7b), a condenser (7c), and an expansion valve (7c) such as a capillary connected in series to circulate a refrigerant. The evaporator (7a) is arranged to dehumidify the process air in the duct (3a). The condenser (7c) is arranged to heat the dehumidified process air in the duct (3a). The control unit (6) is further adapted to operate the refrigerant circuit.
In another alternative embodiment, the laundry dryer (1) is a condenser type (not shown). In this embodiment, the laundry dryer (1) comprises an electrical heater (not shown) for heating the process air and a heat exchanger (not shown) in which the humidity in the process air is condensed by the ambient air.
The present invention also provides a program which has a computer-readable code suitable for causing the laundry dryer (1) to execute the method steps of the present invention. The control unit (5) has memory means (not shown) for storing the program code and a micro processing means (not shown) for performing arithmetic and logical operations.
The present invention also provides a computer-readable recording medium which stores the program of the present invention. In this embodiment, the recording medium is not limited to any particular type of storage medium.
By the present invention, a laundry dryer (1) has been provided that enables quick and reliable sensing of entanglement of clothes. In case of sensing an entanglement, the laundry dryer (1) initiates countermeasures to disentangle the clothes by applying a different rotation regime to the motor, and resumes the drying mode upon successful disentanglement. In case of a forced termination of the disentangling mode or after several repetitions of the entangling mode, a user is audibly and/or visually informed about the entanglement and prompted to manually disentangle the clothes. Thereby, a disentanglement management of the clothes has been improved. In particular, the drying process has been prevented from prolonging and the energy efficiency of the laundry dryer (1) has been enhanced.

Claims

A method for controlling a laundry dryer (1) comprising a drum (2) for receiving clothes to be dried, a motor for rotating the drum (2), a process air circuit (3) for conveying process air through the drum (2) to dry the clothes, a control unit (4) for controlling the motor and the process air circuit (3), wherein the control unit (4) has a normal drying mode for drying the clothes and a disentangling mode for disentangling the entangled clothes, a user interface (5) for receiving user inputs and outputting information and a sensor unit (6) arranged to measure relative humidity of the process air and to output a signal to the control unit (4), the signal being indicative of the measured relative humidity,

the method being characterized by comprising

- a step (S1a-S1d, S3a-S3d) of monitoring a rate of change in the relative humidity of the process air,

- a step (S2) of interrupting the drying mode and initiating the disentangling mode if it is judged that the clothes are entangled based on a monitoring result.
The method according to claim 1, characterized by further comprising

- a step (S4) of terminating the disentangling mode and resuming the drying mode if it is judged that the clothes have been disentangled based on the monitoring result.
The method according to claim 1 or 2, characterized in that the monitoring step (S1a-S1d, S3a-S3d) includes

- a step (S1a, S3a) of measuring relative humidity of the process air,

- a step (S1b, S3b) of calculating a rate of change in the relative humidity based on the measured relative humidity,

- a step (S1c, S3c) of comparing the calculated rate of change in the relative humidity with a threshold rate of change in the relative humidity,

- a step (S1d, S3d) of determining whether the clothes are entangled/disentangled based on the comparison result, wherein it is judged that the clothes are entangled if the calculated rate of change in the relative humidity is greater than the threshold rate of change in the relative humidity and wherein it is judged that the clothes are disentangled if the calculated rate of change in the relative humidity is smaller than the threshold rate of change in the relative humidity.
The method according to any one of claims 1 to 3, characterized in that

in the disentangling mode one or more than one of the following actions are performed in a predetermined sequence,

- a step of stopping the motor,

- a step of reversing rotation direction of the motor,

- a step of rotating the motor at an irregular speed and

- a step of irregularly accelerating/decelerating the motor.
The method according to claim 1, characterized by further comprising

- a step of dispensing with initiating the disentangling mode if the disentangling mode has already been initiated and terminated for more than a predetermined number of times and

- a step of informing a user via the user interface (5) about the judgment that the clothes are entangled and prompting the user to disentangle the clothes manually.
The method according to claim 5, characterized by further comprising

- a step of resuming the drying mode after the user has disentangled the clothes manually.
A laundry dryer (1) comprising

- a drum (2) for receiving clothes to be dried,

- a motor for rotating the drum (2) and

- a process air circuit (3) for conveying process air through the drum (2) to dry the clothes,

characterized by further comprising

- a control unit (4) for controlling the motor and the process air circuit (3), wherein the control unit (4) has a normal drying mode for drying the clothes and a disentangling mode for disentangling the entangled clothes,

- a user interface (5) for receiving user inputs and outputting information and

- a sensor unit (6) arranged to measure relative humidity of the process air and to output a signal to the control unit (4), the signal being indicative of the measured relative humidity,

wherein the control unit (4) is configured to execute the methods steps according to any one of steps 1 to 6.
A program comprising computer-readable code for causing a laundry dryer (1) to execute the method steps according to any one of claims 1 to 6.
A computer-readable recording medium storing the program according to claim 8.