EP3741909B1

EP3741909B1 - A control method for drying machines

Info

Publication number: EP3741909B1
Application number: EP20175633.5A
Authority: EP
Inventors: Elif Gul GOCER; Tugba CICEK; Asli CERIT ADSAY
Original assignee: Vestel Beyaz Esya Sanayi ve Ticaret AS
Current assignee: Vestel Beyaz Esya Sanayi ve Ticaret AS
Priority date: 2019-05-23
Filing date: 2020-05-20
Publication date: 2022-03-02
Anticipated expiration: 2040-05-20
Also published as: EP3741909A1; TR201907847A2

Description

TECHNICAL FIELD

The present invention relates to a control method for drying machines to distinguish problems causing temperature increase in the machine and inform the user properly so that the necessary precautions are taken.

BACKGROUND OF THE INVENTION

In the drying machines, feathers and fibres separated from the laundry and mixed with air throughout the drying process are collected at a fluff filter, also known as a door filter or a fibre filter. The fluff filter should be cleaned by the user after each drying process. In the drying machines, in addition to the fluff filter, there is also provided a filter known as a condenser where the fibres escaping from the fluff filter are collected. Clogging of the filters cause reduction in performance of the machine, increase in the energy consumption and a prolonged drying period. Furthermore, clogging of the filters may cause the drying machine to heat suddenly and excessively, which may damage the machine in the long term, pose a risk of fire, damage the laundry inside the drum and/or cause the user to experience sudden temperature when she/he opens the door. Apart from clogging of said filters, reasons like malfunctioning of a motor of the machine may cause a temperature increase; and failing to respond the specified problem at the right time may result in machine damage. Therefore, in the drying machines, it is important to detect the reason of the temperature increase and inform the user if an unexpected temperature increase occurs.
According to the known state of art, various applications are provided to overcome said problems. One of these applications is disclosed in US4622759A . In this document, a control system and method for drying devices are disclosed, wherein in the method, an exhaust temperature of the dryer is monitored and compared with a threshold value. If the exhaust temperature or a change in the exhaust temperature exceeds the threshold value, power supplied to a heater is cut off in a first control process, and power supplied to the heater and a motor is cut off in a second control process. However, said method remains incapable of detecting the reason of the temperature increase.
Patent document no. US2008072450A1 discloses a clogging detection system for drier. According to this document, in order to determine the clogging in an air passage, temperature values of the heater and air passage are used. However, system disclosed in this document cannot distinguish the situations when there is problem with fan motor and when the clogging occurs.
Another patent document no. US2008148597A1 discloses a dryer with clogging detection function. Similar to patent document no. US2008072450A1 , this documents also determine the clogging situation by using temperature values of the heater and air passage. Therefore, this document also fails to distinguish the situations when there is problem with fan motor and when the clogging occurs.
Another patent document no. EP3299512A1 a control method for laundry drying machine and a laundry drying machine. According to this document, in order to determine plugging of a lint filter, a difference between the compressor outlet temperature and the drum outlet temperature is used. Although one reason for said temperature difference is plugging of the lint filter, it is not the only reason. Therefore, method of this document cannot determine the filter plugging correctly.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is defined in claim 1. A preferred embodiment is defined in dependent claim 2.

OBJECT OF THE INVENTION

An object of the present invention is to provide a control method to detect and distinguish problems occurring in the drying machines and causing temperature increase.
Another object of the present invention is to provide a control method to inform the user about the problem occurred so that the necessary precautions are taken.
A further object of the present invention is to provide a reliable control method.

DESCRIPTION OF THE INVENTION

In the drying machines, feathers and fibres separated from the laundry and mixed with air throughout the drying process are collected by a filter, also known as fluff filter and condenser. Clogging of these filters cause reduction in performance of the machine, increase in the energy consumption and a prolonged drying period. Furthermore, clogging of the filters may cause the drying machine to heat suddenly and excessively, which may damage the machine in the long term, pose a risk of fire, damage the laundry inside the drum and/or cause the user to experience sudden temperature when she/he opens the door. Apart from clogging of said filters, reasons as malfunctioning of a motor of the machine may cause a temperature increase; and failing to respond the specified problem at the right time may result in machine damage. Accordingly, with the present invention, there is provided a control method to inform the user about the problem occurred so that the necessary precautions are taken, in case an unexpected temperature increase occurs. The control method according to the invention is for use in a drying machine as defined in claim 1.
In an exemplary embodiment of the invention, the user initiates a drying program via e.g. a control panel of the drying machine by choosing one of the stored drying programs and determining the parameters regarding the drying process. The drying program may comprise a drying phase during which the drying process is performed and a cooling phase during which a temperature of the machine and the laundry is decreased after completion of the drying process, wherein after completion of the drying phase and the cooling phase, a finishing mode is adopted during which the motor and the heater are turned off/stopped. Upon initiating the drying program, the drying phase is initiated as well, and the motor and the heater are activated. During the drying program and preferably the drying phase, the first measurement unit measures a temperature of the heater in a first period which may be e.g. instant/once at a second etc., and the second measurement unit measures a temperature of the motor in a second period. The control unit compares the temperature value measured by the first measurement unit with a first threshold value, and repeats this process as long as the temperature value is below the first threshold value. If the control unit detects that temperature value measured by the first measurement unit is equal to or above the first threshold value, it allows the heater to be turned off and compares the temperature value measured by the first measurement unit with the first threshold value after a first time period. If the control unit detects that temperature value measured by the first measurement unit is below the first threshold value following said comparison, it compares periodically the temperature values measured by the first measurement unit with a second threshold value, thereby controlling whether a temperature of the heater decreases below the second threshold value. Until it is detected that the temperature of the heater (the temperature value measured by the first measurement unit) has decreased below the second threshold value, the drying program (the drying phase) is continued such that the heater is turned off and the motor is in operation; and when it is detected that the temperature of the heater has decreased below the second threshold value, the heater is re-activated and the program is resumed on. If it is detected that the temperature values measured by the first measurement unit are equal to or above the first threshold value, the control unit detects whether the temperature values measured by the second measurement unit have decreased or not. Said detection process can be performed by the control unit by comparing the temperature values measured by the second measurement unit with each other. For example, the control unit is able to receive temperature values measured by the second measurement unit and compare them with a previous temperature value periodically. In said embodiment, the control unit may comprise a memory unit so that a received measurement value can be compared with a previous temperature value that is stored at the memory unit. When it is detected that the temperature values of the motor measured by the second measurement unit have decreased, non-operational state of the motor is determined and a finishing mode is adopted, the motor and the heater are stopped and a motor error warning is provided by the warning unit. If it is detected that the temperature values detected by the second measurement unit have not decreased, operational state of the motor is determined; and until the temperature value measured by the first measurement unit decreases below the second threshold value, the state that the heater is turned off and the motor is in operation is continued; and when said temperature value decreases below the second threshold value, the heater is re-activated and the program is resumed on. Following that process, if an unexpected temperature increase is detected at the machine, the same process steps are repeated.
In a preferred embodiment of the invention, if the temperature of heater (e.g. the temperature value received by the first measurement unit) increases above the first threshold value more than once (preferably by a reference value) during the drying program, the control unit turns off the heater and a cooling phase is carried out. In said embodiment, the warning unit provides a filter clogged warning when the program is completed.
With the control method according to the invention, temperature of the motor and the heater is monitored, and a reason for a temperature increase occurred in the machine is determined by evaluating a change in the temperature values. Therefore, the user can be informed that the generated temperature is due to a motor failure or the filter being clogged, and thus, the user cleans the filter or calls a technical service in case of a motor error to eliminate the error.

Claims

A control method for a drying machine which comprises at least one drum for receiving items to be dried; at least one motor for enabling the drum to perform rotational movement; at least one heater for increasing a temperature inside the drum so that a drying process is performed; at least a first measurement unit in connection with the heater and measuring temperature of the heater; at least a second measurement unit in connection with the motor and measuring temperature of the motor; at least one filter where feathers and fibres separated from the laundry and mixed with air throughout the drying process are collected; at least one warning unit for providing the user with a visual and/or auditory warning; and at least one control unit which is in connection with the motor, the heater, the first measurement unit, the second measurement unit and the warning unit, characterized by comprising the steps of:
- initiating a drying program by the user;

- activating the motor and the heater upon initiation of the drying program;

- measuring the temperatures periodically by the first measurement unit and the second measurement unit throughout the drying program;

- comparing, by the control unit, the temperature measured by the first measurement unit with a first threshold value;

- if the temperature value measured by the first measurement unit is below the first threshold value, returning to the step of comparing the temperature value measured by the first measurement unit with the first threshold value;

- if the temperature value measured by the first measurement unit is equal to or above the first threshold value, turning off the heater by the control unit;

- at the end of a first time period after the heater is turned off, comparing, by the control unit, the temperature value measured by the first measurement unit with the first threshold value;
o if the temperature value measured by the first measurement unit is below the first threshold value, comparing, by the control unit, the temperature values measured by the first measurement unit with a second threshold value in a third period;
▪ continuing the program such that the heater is turned off and the motor is in operation until it is detected that the temperature value measured by the first measurement unit has decreased below the second threshold value;

▪ if it is detected that the temperature value measured by the first measurement unit has decreased below the second threshold value, re-activating the heater, and returning to the step of "measuring the temperatures periodically by the first measurement unit and the second measurement unit" and resuming on the program;

o if the temperature value measured by the first measurement unit is equal to or above the first threshold value, detecting by the control unit whether the temperature values measured by the second measurement unit have decreased or not, wherein decreasing of the temperature values measured by the second measurement unit is detected by comparing temperature values measured by the second measurement unit with previous temperature value periodically;
▪ if the temperature values measured by the second measurement unit are decreasing, proceeding to a finishing mode, during which the motor and the heater are turned off/stopped, and giving a motor error warning by the warning unit;

▪ if the temperature values measured by the second measurement unit are not decreasing, returning to the step of "continuing the program such that the heater is turned off and the motor is in operation until the temperature value measured by the first measurement unit decreases below the second threshold value".
A control method according to claim 1, characterized by comprising the steps of: if the temperature value received by the first measurement unit increases above the first threshold value by a reference value, the control unit proceeds to a cooling phase and the warning unit provides a filter clogged warning when the program is completed.