A WASHER/DRYER

[0001] The present invention relates to a washer/dryer wherein the position and amount of the unbalanced load is detected.

[0002] In washer/dryers, the laundry emplaced in the drum clings to the inner walls of the drum due to the effect of the centrifugal force particularly during rotation at high speed. Displacements occur in the rotational axis of the drum depending on the position of the laundry not distributed homogeneously. This condition causes the machine to vibrate and to make unwanted movements.

[0003] The imbalance can be counterbalanced by placing an equal amount of load opposite the unbalanced load in order to avoid this situation and to balance the system. However, as long as the position and amount of the unbalanced load is not detected accurately, the counterbalancing load does not show the intended effect and the washer/dryer cannot be operated efficiently.

[0004] A lot of research is done in the technique for finding the position and amount of the unbalanced load.

[0005] In the state of the art United States of America patent application no

US2004103485, a washing machine is described wherein the amount of load emplaced in the washing machine is detected with the data received from rotating the motor 2/5 revolutions, measuring the revolution time period for this process and the acceleration curve.

[0006] In the state of the art German patent application no DE19832292, in a direct drive washing machine, predicting the load by measuring the position reached by the laundry batch loaded in the drum while the drum rotates and the electric current values of the electric motor is described.

[0007] In the state of the art Japanese patent application no JP2006311884, a vibration detecting means is used that can detect vibrations in at least two axes for determining the unbalanced load. In this case, when the phase difference of the signals of the vibration detecting means at two directions and the data of front, rear are used together, the position of the unbalanced load can be found. However, the sinusodial signals used here are not only generated due to the oscillation of the drum but are also affected by the environmental noise.

[0008] The object of the present invention is to realize a washer/dryer that detects the position and amount of the unbalanced load.

[0009] The washer/dryer designed to fulfill the object of the present invention, explicated in the first claim and the respective claims thereof, comprises two sensors that are used to detect the position and amount of the unbalanced load which is caused by piling up of laundry on one side of the drum particularly at high speeds.

[0010] One of the sensors is a position sensor that generates a pulse signal for every revolution the drum rotates depending on the movement of a magnet disposed on the drum.

[0011] The second sensor is a vibration sensor that generates a sinusodial signal similar to the oscillation of the drum that oscillates as a result of the unbalanced load. The frequency of this signal is equal to the rotational frequency and the amplitude of the signal is in direct proportion with the amount of the unbalanced load for every constant speed revolution. The amount of the unbalanced load is detected by looking at the amplitude and the variance of the signal at the rotational speed of the drum. For example, vibration sensor can be used as piezoelectric sensor.

[0012] The washer/dryer furthermore comprises a control unit that detects the angular position of the load by calculating the phase difference between the signals generated by these two sensors.

[0013] In an embodiment of the present invention, the position wherein the unbalanced load is at the same horizontal level with the magnet is the reference position. In the embodiment wherein the load is in the reference position, the rotational speed of the drum causing imbalance and the measured phase difference are recorded in the control unit as the reference phase difference.

[0014] In an embodiment of the present invention, the phase difference is different from the reference phase difference in the conditions wherein the load is not at the same horizontal level with the magnet. This difference gives the angular position of the load, in other words the distance with respect to the reference position.

[0015] In another embodiment of the present invention, the control unit comprises a control method for distributing the unbalanced load the angular position of which is detected. For example, the imbalance is avoided by sending a balancing load of a determined amount to a position opposite the angular position of the unbalanced load in the drum, with respect to the drum center. The balancing load is a fluid load, which is movable and preferably amount adjustable, fastened to the outer wall of the drum.

[0016] In an embodiment of the present invention, the position sensor is made up of a magnet in the drum belt pulley and a hall sensor behind the tub facing this magnet.

[0017] By means of the washer/dryer of the present invention, the position and amount of the unbalanced load can be detected accurately and thus the necessary balancing methods can be used effectively.

[0018] The washer/dryer designed to fulfill the object of the present invention is illustrated in the attached figures, where:

[0019] Figure 1 - is the sideways schematic view of a washer/dryer.

[0020] Figure 2 - is the rear schematic view of an embodiment of the present invention.

[0021] Figure 3 - is the graph showing the signals used in determining the position and amount of the load in an embodiment of the present invention.

[0022] The elements illustrated in the figures are numbered as follows:

1. Washer/dryer

2. Tub

3. Drum

4. Motor

5. Magnet

6. Position sensor

7. Vibration sensor

8. Control unit

[0023] The washer/dryer (1) of the present invention comprises a tub (2), a drum (3) disposed inside the tub (2), wherein the laundry is emplaced, rotating around a horizontal axis (E) and a motor (4) for rotating the said drum (3). [0024] The washer/dryer (1 ) furthermore comprises

- a magnet (5) situated on the drum (3),

- a position sensor (6) disposed on the tub (2) that generates a pulse signal (D) at each rotation of the drum (3) by the effect of the magnet (5),

- a vibration sensor (7) disposed on the tub (2), generating a sinusodial signal (S) having the rotational frequency of the drum (3) and

- a control unit (8) that detects the amount of the unbalanced load (Y) by looking at the amplitude (λ) of the sinusodial signal (S) and finds the angular position of the unbalanced load (Y) by measuring the phase difference (F) between the pulse signal (D) and the sinusodial signal (S) (Figure 1 and Figure 2).

[0025] Particularly in the spinning step, the laundry clings to the drum (3) wall and stays in a certain angular position throughout the spinning step. The drum (3) starts to rotate in an unbalanced manner as the laundry piles up on one side of the drum (3). The amount of load causing the imbalance is called the unbalanced load (Y).

[0026] The magnet (5) which is not on the rotational axis (E) of the drum (3) changes place continuously as the drum (3) rotates. The position sensor (6) generates a pulse signal (D) at every encounter with the magnet (5). The vibration sensor (7) generates a sinusodial signal (S) by measuring the vibrational amplitude in the drum (3). The amplitude (λ) of the sinusodial signal (S) generated by the vibration sensor (7) is in direct proportion to the amount of the unbalanced load (Y) while the drum (3) rotates at constant speed. The amount of the unbalanced load (Y) is found by comparing the variance between the amplitudes of the signals calculated at the predetermined reference rotational revolutions and the amplitude (λ) of the sinusodial signal (S). The variance in the amount of the unbalanced load (Y) does not change the phase of the sinusodial signal (S) (Figure 3).

[0027] The control unit (8) regulates the operational process of the washer/dryer (1) in accordance with the position of the unbalanced load (Y) detected by the difference of phase between the pulse signal (D) received from the position sensor (6) and the sinusodial signal (S) received from the vibration sensor (7) and the amount of the unbalanced load (Y) detected from the amplitude (λ) of the sinusodial signal (S). The control unit (8) uses balance maintaining methods when the amount of vibration due to the unbalanced load (Y) exceeds a level predetermined by the producer and accordingly the washer/dryer (1) continues operating in a safe manner.

[0028] In the preferred embodiment of the present invention, the position of the unbalanced load (Y) aligned in the horizontal axis with respect to the magnet (5) and the position sensor (6) for every different rotational revolution is recorded in the control unit (8) by the producer as the reference position (R). When the unbalanced load (Y) is in the reference position (R), the phase difference (F) between the measured pulse signal (D) and the sinusodial signal (S) is recorded in the control unit (8) as the reference phase difference (RF) for every different rotational revolution. For example, when the unbalanced load (Y) is in the reference position (R), the reference phase difference (RF) is recorded as 40 degrees in the control unit (8) measured at 800 rpm rotational revolution, and the reference phase difference (RF) is recorded as 45 degrees measured at 1000 rpm rotational revolution by the producer.

[0029] In an embodiment of the present invention, the phase difference (F) measured when the unbalanced load (Y) is not at the reference position (R) is different from the reference phase difference (RF). This difference shows how much the angular position of the unbalanced load (Y) changes with respect to the reference position (R) (Figure 3). For example, when the reference phase difference (RF) at 1000 rpm is 40 degrees, and when the unbalanced load (Y) is displaced 10 degrees in the drum (3) with respect to the reference position (R), the phase difference (F) goes down to 30 degrees or goes up to 50 degrees with respect to the rotational direction of the drum (3). The phase difference (F) is calculated by dividing the time difference (T) by the period (P) and multiplying by 360 (Figures 3 and 4). Thus, the position of the unbalanced load (Y) in the drum (3) can be found with respect to the reference position (R). [0030] In an embodiment of the present invention, the magnet (5) is disposed on the belt pulley behind the drum (3). Thus, the reference position (R) is determined on an axis parallel (RE) to the rotational axis (E) of the drum (3). The different positions of the unbalanced load (Y) that change at each washing, which show variability depending on the type and amount of the washed laundry can be found easily by detecting the degree of distance from this reference axis (RE) (Figure 1).

[0031] In an embodiment of the present invention, the washer/dryer (1) comprises a position sensor (6) that is disposed on the projection of the path followed by the magnet (5) over the tub (2).

[0032] In the preferred embodiment of the present invention, the position sensor (6) is a Hall effect sensor and the vibration sensor (7) is a piezoelectric sensor. The position of the unbalanced load (Y) can be detected accurately since the position sensor (6) generates a pulse signal (D) that is affected minimally by noise. The phase difference (F) is net phase difference measured by means of using two different sensors (6 and 7) and the angular position can be calculated correctly. In order to reach the most effective results, the position sensor (6) is disposed on the rear wall of the drum (3), aligned with an axis parallel to the rotational axis (E) of the drum (3) and the vibration sensor (7) is disposed on the tub (2).

[0033] In the washer/dryer (1) of the present invention, since the position and amount of the unbalanced load (Y) can be detected accurately, the necessary balancing methods can be used effectively. Accordingly, the washer/dryer (1) can operate safely and the unwanted vibrations are prevented.

[0034] It is to be understood that the present invention is not limited to the embodiments disclosed above and an expert in the technique can easily introduce different embodiments of the present invention. These should be considered within the scope of the protection postulated by the claims of the present invention.