Sanyo Electric Co., Ltd.

Yoshitaka Tsunomoto

Tomohiko Ikeda

Masafumi Nishino

Kenji Yamamoto

Harumi Takeuchi

Katsuhito Nakagawa

Masakatsu Morishige

Akira Takenaka

Kouichi Hatsuda

Kiyonori Tamura

Mosakatsu Morishige

The present invention proposes a washing machine having a simple-structured mechanism for correcting the balance of the drum. In an embodiment of the present invention, plural water-holding chambers are located at the back of the drum around the rotation axis. The water-holding chamber has an opening for introducing water from a water discharge port . At the start of an extracting operation, all the water-holding chambers are emptied by rotating the drum at low speed. After that, when the eccentric load due to an uneven distribution of the laundry is greater than an upper limit value, the drum is rotated at a preset speed and a water supply valve is opened. Thus, the water from the water discharge port is supplied into all the water-holding chambers, and the water is held in the water-holding chamber by the centrifugal force. After that, the speed of the drum is temporarily reduced at a time point corresponding to the position of the eccentric load, whereby a part of the water held by one or some of the water-holding chambers at or close to the position of the eccentric load is let to spill out from the chamber. After thus canceling the load unbalance of the drum around the rotation axis as a whole, the drum is rotated at high speed for extraction.

Washing machine

The invention relates to a spin extractor for extracting liquid from wet laundry by rotating a drum with the laundry contained therein at high speed about a horizontal axis. In an inventive spin extractor, while an operation controller controls the speed of the drum so that the laundry is slightly pressed on the inner peripheral wall of the drum by centrifugal force and rotates with the drum, a position detector detects the position of an eccentric load due to the laundry as a first position. Then, the speed of the drum is raised to a second speed for weak extraction, which is lower than a predetermined maximum speed for extraction, and the position detector detects the position of the eccentric load as a second position. A quality determiner checks the displacement of the second position from the first position to determine the uniformity in extraction quality of the articles, where the extraction quality of an article represents how easily liquid is extracted therefrom. When the uniformity in the extraction quality is low, the weights of the articles decrease unevenly through the weak extraction, which causes a change in the position of the eccentric load. So, when, the displacement of the position is greater than a preset value, the operation controller sets an extraction speed lower than the maximum speed, and rotates the drum at the extraction speed during the extraction, whereby abnormal vibration is avoided.

Spin extractor

In a spin extractor, an eccentric load judging unit judges the magnitude of the eccentric load based on the amplitude of fluctuations in the motor current while a drum is rotated at a speed at which the centrifugal force on fabric articles contained in the drum is a little larger than the gravity. If the magnitude of the eccentric load detected is larger than predetermined, a balance correcting operation is conducted by a speed control unit. That is, a speed reducing position designating unit sends a pulse signal to the speed control unit at the moment when the eccentric load of the drum comes just before the highest position, in response to which the speed of the drum is reduced momentarily. When the speed is reduced, the centrifugal force is smaller than the gravity, so that the fabric articles crammed and piled fall off the inner peripheral wall of the drum. Thus the fabric articles can be scattered almost evenly.

In a spin extractor according to the present invention, a basket drum for containing fabric articles is provided with a balance weight in a portion of its inner peripheral wall, giving the drum its own eccentric load. The magnitude and position of the resultant eccentric load constituted by both the drum's own eccentric load and the fabric articles unevenly distributed therein is detected based on the fluctuations in the motor current. If the magnitude of the eccentric load is out of a predetermined range or if the position of the eccentric load is not in the proximity to the position opposite at an angle of 180.degree. to the balance weight, the drum is rotated at such a speed that the centrifugal force acting on the fabric articles in the drum is smaller than the gravity force. Thus, the fabric articles are loosened, scattered and redistributed, and the magnitude and position of the eccentric load satisfy the required condition. The above-mentioned range is predetermined based on the magnitude of the eccentric load that causes no abnormal vibration in the extracting operation, taking account of both the weight of the balance weight and the decrease in the weight of the fabric articles through the extracting operation. After the magnitude and position of the eccentric load are settled to satisfy the required condition, the drum is rotated at full speed to extract liquid from the fabric articles.

A washing machine comprises a tub, in which a pulsator is rotatably arranged. The pulsator is driven by a motor positively or reversely. When a start switch is pressed, first an initial cycle is started for a relatively short period of time to dissolve detergents. When this initial cycle is completed, a main cycle is started, during which the pulsator repeats positive and reverse rotations with intervals. The main cycle is arranged to continue for a set period of time, into which auxiliary cycles shorter than the main cycle are intermittently inserted. The positively and reversely rotating times of the adjoining repeating units included in the main cycle differ with each other. In the auxiliary cycle, its repeating unit involves a relatively longer rotating time or a shorter recess time of the pulsator as compared with the repeating unit constituting the main cycle. Accordingly, during the auxiliary cycle, a water current stronger than that in the main cycle is produced, thus restraining the 'entangling clothes' during a washing process.

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Otsu, Japan

Yoshitaka Tsunomoto