The present invention relates to a method for testing the operation of washing machines, see EP-A-1 696 067.

Concerning the electronic household appliances, one or more components thereof may become malfunctioning, either because of environmental conditions of the respective appliance, or because of user faults. A household appliance having a malfunctioning component mostly fail to operate. When a problem is encountered in a household appliance according to the prior art, it is brought to technical service in order to troubleshoot and solve the problem. This, in turn, results in energy and time loss.

In the patent document DE102006049628A1 according the prior art is disclosed a washing machine of which a heater is tested. The functionality of said heater is tested using a robot. In that method, however, the test cannot be conducted at everywhere since a robot is used, and therefore that test method is expensive.

In another patent document W02008154711A2 according the prior art is disclosed a washing machine system. The time to run the machine can be set by a user, using a timer button. The washing machine can also be switched to a self-check mode using this button. In said check mode, the functioning of various components of the machine is tested automatically by the machine.

The present invention discloses a test method for washing machines comprising at least one control element; at least one warning element providing the user with information on the operative state of the machine; at least one heating element heating the water to be used in the machine; at least one temperature sensor measuring the temperature of heated water; at least one electronic control unit regulating the operation of the machine, and at least one door through which items to be washed are placed.

Said method comprises the steps of- initiating the test process once the closing of the door and the use of the control element in a determined order and/or combination are detected by the electronic control unit; checking if there is present a required amount of water in the machine for the test; supplying water if the amount thereof is not adequate; measuring again the amount of water; terminating the test if there is not present an adequate amount of water by providing a 'water failure indicator' or 'valve failure indicator'; checking the operation of the temperature sensor in the machine by measuring the temperature of the water in the machine if there is present an adequate amount of water in the machine before or after water is supplied to the machine; terminating the test by sending a failure signal to the warning element if no signal is supplied from the temperature sensor to the electronic control unit; measuring the temperature of water in the machine and storing this measured value if a signal is received from the temperature sensor; activating the heater in the machine throughout a predetermined time interval; measuring back the temperature value of water in the machine at the end of this time interval; comparing the finally-measured temperature value to an initial temperature value stored in the electronic control unit; and inferring a failure in the operation of the heater and/or temperature sensor if the difference between these two temperature values is lower than a predetermined threshold value.

According to the present invention, when a failure is detected in the machine, a warning is indicated on the warning element of the machine so that the person conducting the test sees the presence of a failure.

The object of the present invention is to develop a method for testing the heater and temperature sensor of a washing machine.

Another object of the present invention is to develop a method for detecting any heater failure and temperature sensor failure in the washing machine without having to bring the machine to a technical service.

A further object of the present invention is to develop a method by which the operation of the heater and temperature sensor is tested by an authorized person.

Said objects are achieved by the test method according to claim 1.

Illustrative embodiments of the washing machine test method according to the present invention are illustrated in annexed figures briefly described hereunder.

• Figure 1 is a perspective illustration of the washing machine.
• Figure 2 is a cross-sectional illustration of the washing machine.
• Figure 3 is a flowchart of the test method.

The parts in said figures are individually referenced as following. washing machine (M) temperature value (T_0,T₁) control element (1, 2) door (3) warning element (4) heater (5) temperature sensor (6) initiation (10) door locking (11) lock check (12) water-level check (13) sensor check (14) temperature storing (15) heater activating (16) new temperature storing (17) temperature comparing (18) water supplying (19) water-level recheck (20) failure sending (21) water-failure sending (22) lock-error sending (23) completion (24)

In electronic household appliances, one or more components thereof may become malfunctioning, either because of environmental conditions of the respective appliance, or due to user faults. Particularly, when the water used in washing machines has a high limescale content, the latter deposits on the heating element and/or temperature sensor and causes these components to fail. These components may also fail due to environmental factors, user faults and/or production errors. Thus, a method is developed with the present invention for testing these components.

The washing machine (M), illustrated as a clothes washer in figures 1 and 2, comprises at least one control element (1, 2), which controls the operation of the machine (M) and may be in the form of at least one button or switch; at least one warning element (4) providing the user with information on the operative state of the machine (M); at least one heater (5), preferably in the form of at least one resistance to heat the water to be used in the machine (M); at least one temperature sensor (6) measuring the temperature of heated water; at least one electronic control unit (not illustrated in figures) regulating the operation of the machine (M), and at least one door (3), through which items to be washed are placed into the machine (M). Said warning element (4) may comprise at least one speaker alerting the respective user in an audible manner, and/or at least one indicator (e.g. display, illuminant) warning the respective user visually.

According to the test method developed with the present invention, first the door (3) of the machine (M) is closed in order to test the heater (5) and temperature sensor (6) of the machine and the control elements (1, 2) are run in a predetermined order and/or combination. With this order and/or combination being detected by at least one control unit (not illustrated in figures) on a software basis, the test process, with an exemplary flowchart shown in Figure 3, is initiated (10). First, it is checked if there is present a required amount of water (13) in the machine (M) (13), and if this amount is inadequate, water is supplied to the machine (19). The water amount in the machine (M) is measured again (20), and if the water amount supplied is not adequate, the test is terminated (24) by indicating a water-failure or valve-failure (22) on the warning element (4). If there is present an adequate amount of water in the machine (M) before or after water is supplied (19) to the machine (M), it is checked if the temperature sensor (6) in the machine (M) is active or not (14). For this check, the temperature sensor (6) is required to measure the temperature of water taken into the machine (M) and transmit this data to the control unit in the form of a signal. If no signal is transmitted from the temperature sensor (6) to the control unit, a failure signal is sent to the warning element (4) and the test is terminated (24). If a signal is received from the temperature sensor (6), the temperature of water in the machine (M) is measured and transmitted to the control unit (15). The temperature value (To) sent to the control unit is stored in the control unit. Then, the heater (5) of the machine (M) is activated for a predetermined amount of time (preferably between 10 to 30 minutes and specifically 15 minutes), such that the water present in the machine (M) is heated (16). At the end of this period, the temperature value (T₁) of water in the machine (M) is measured again (17), and this value (T₁) is compared to the initial temperature value (To) stored in the control unit (18). Thus, it is checked if there is a failure in the heater (5) and/or temperature sensor (6). If the difference between these two temperature values (T₁-T₀) is lower than a predetermined threshold value (preferably 1-3°C, and specifically 2°C), it is inferred that a failure exists in the heater (5) and/or temperature sensor (6), and the test is terminated (24) by transmitting a failure signal (21) to the warning element (4). If said difference (T₁-T₀) is higher than the threshold value, the test is completed (24).

According to a preferred embodiment of the present invention, the door (3) of the machine (M) is automatically locked once the test process is initiated (10), and it is checked if the lock is activated or not (12). If the lock has achieved its activated state, it is switched to the step of measuring the water level in the machine (13), whereas if the lock is not activated, the test is terminated (24) by providing a lock error indication (23).

According to an alternative embodiment of the present invention, the test process is conducted remotely via a network. In this embodiment, the test results are transmitted to the person conducting the test via the network.

In terms of the present invention, the control elements are to be used in a determined order and/or combination to have the machine (M) switched to the test mode. This, in turn, makes sure that the test process is conducted at places and times only, which the authorized persons determine. Thus, it is both ensured to test the machine (M) in situ (e.g. at home), and to prevent the machine (M) from being switched to the test mode by unauthorized persons.