Textiles: fluid treating apparatus – Machines – Single tub and automatic sequential operation mechanism
Reexamination Certificate
2000-03-16
2002-10-08
Coe, Philip (Department: 1746)
Textiles: fluid treating apparatus
Machines
Single tub and automatic sequential operation mechanism
C068S012050, C068S012060, C068S012270
Reexamination Certificate
active
06460381
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a washing machine or an apparatus having a rotatable container.
BACKGROUND OF THE INVENTION
Washing machines are provided with various kinds of sensors and detectors such as: a load detector for detecting the weight of the laundry contained in a wash-and-extraction tub (which is referred to as “laundry tub”); a level sensor for measuring the water level in the laundry tub; and a vibration sensor for detecting an abnormal vibration which occurs in the course of an extracting process if the laundry tub is rotated with the laundry being distributed unevenly.
Japanese Unexamined Patent Publication No. S63-206283 discloses one of conventional methods of detecting the weight of the laundry. The method includes steps of:
turning on a motor for rotating a pulsator provided at the bottom of the laundry tub with no water held in the tub and then turning off the motor after a preset time period; counting pulse signals produced synchronously with the rotation of the motor after the motor is turned off;
and calculating the weight of the laundry based on the number of pulses produced until the motor stops the inertial rotation. In this process, the pulsator stops sooner as the weight of the laundry is larger. Accordingly, the weight of the laundry is determined larger as the number of pulses is smaller. By such a method of detecting the weight of the laundry utilizing the inertial rotation of the pulsator, however, it is difficult to improve the accuracy of detection because the detected value varies depending on the quality or condition of the fabric of the laundry. Another problem is that the laundry is often damaged due to the friction between the pulsator and the laundry.
In some of the conventionally proposed methods, a weight sensor is used for directly measuring the weight of the laundry contained in the washing tub, instead of detecting the weight indirectly. For example, Japanese Unexamined Patent Publication No. H5-84382 discloses a washing machine, where a weight sensor composed of a spring, coil, core and other elements is provided on suspension rods with which the washing tub is suspended. According to this construction, when the load on the suspension rods change and the suspension rods move up or down, the length of the part of the core in the coil held at a fixed position changes, and the inductance of the coil changes accordingly.
When the above-described weight sensor is used, however, the damping design becomes complicated because two types of spring (one for damping and the other for detecting weight) are provided at one or some of the suspension rods while a single spring is provided at other rods. Also, the weight sensor itself may increase the vibration, because the spring used in the weight sensor has its own natural frequency. Also, the use of the above described weight sensor is not preferable in respect of designing the washing machine with smaller size and greater capacity, because the weight sensor is normally large in size so that it occupies a substantial space in a body housing of the washing machine. Also, the characteristics of the spring of the weight sensor changes or deteriorates as the spring ages, which deteriorates the detection accuracy.
Another problem concerning the weight sensor is as follows. In the above-described washing machine, the weight sensor is used for detecting not only the weight of the laundry contained in the laundry tub but also the weight of water supplied and held in the outer tub. The weight of the laundry is several kilograms at most, while that of water held in the outer tub is almost ten or more times as great as that of the laundry. When the weight sensor is designed to detect a weight as great as several tens of kilograms, the detection accuracy of a weight as small as the weight of the laundry becomes inevitably low. When, on the other hand, the weight sensor is designed to detect a weight as small as the weight of the laundry with adequately high accuracy, the maximum weight that the weight sensor can detect cannot be as great as that of the water held in the outer tub. Thus, it is difficult to detect both the weight of the laundry and that of water held in the outer tub with the above-described weight sensor.
SUMMARY OF THE INVENTION
Taking account of the above-described problems, one object of the present invention is to provide a washing machine with a small-sized load sensor having high detection accuracy without introducing difficulties in the damping design and without causing unfavorable effect on the rotation of the laundry tub. Another object of the present invention is to utilize the load sensor not only for detecting the weight of the laundry but also for detecting the weight of water and further for detecting water level in the outer tub. Still another object is to provide a washing machine having a sensor whereby the vibration of the laundry tub and/or the outer tub is detected with high accuracy during the extracting process where the laundry tub spins at high speed.
For solving the above-described problems, a washing machine according to the present invention utilizes a pressure sensor constructed with a magnetostrictive element whose magnetic characteristic changes depending on the changing rate or magnitude of an external force exerted on it. A pressure sensor of this type is disclosed, for example, in the full text of Japanese Unexamined Utility Model Publication No. H1-105834.
Thus, in a washing machine including a body housing, an outer tub suspended in the body housing and a wash-and-extraction tub rotatably provided in the outer tub, the washing machine according to a first aspect of the present invention (which is referred to as “first washing machine” in this specification) includes a pressure sensor placed at a position where it experiences an external force due to the weight of the laundry contained in the wash-and-extraction tub and the weight of water held in the outer tub. The pressure sensor is constructed with a magnetostrictive element on which the external force is exerted and a coil placed close to the magnetostrictive element. The coil is used for detecting a change in the magnetic characteristic of the magnetostrictive element due to the external force. A measuring part receives an output of the coil of the pressure sensor and measures the weight of the laundry and the weight of the water based on the output. An operation controller controls the water supply into the outer tub based on the weight measured by the measuring part. First, before the start of the water supply, the operation controller determines an object amount of water to be supplied into the outer tub according to the weight of the laundry. Next, while the water is being supplied, the operation controller monitors the weight of water with the measuring part and controls the water supply with respect to the object amount of water.
The above-described pressure sensor is advantageous in that it is small and lightweight, and that it has a broad detection range. Since it occupies a very small space, the pressure sensor can be placed anywhere in the washing machine and allows designing washing machines of smaller in size and greater in capacity. Also, the pressure sensor never functions as a source of vibration because it includes no moving element such as a spring. Since no moving element is used, further, detection accuracy never deteriorates due to degeneration of the moving element.
The above-described pressure sensor has such an advantage that it can detect a broad range of external force and that its sensitivity is higher as the external force is smaller. Therefore, when it is desired to measure both the weight of the laundry and the weight of water with a single pressure sensor, the above-described sensor may be preferably used. For example, based on the output of the above-described pressure sensor, the measuring part not only measures the weight of the laundry with high sensitivity before water is supplied, but also measures the weight of water, which increases be
Aoki Hideaki
Hiyamizu Kazuya
Kakutani Kazushige
Kishimoto Keiji
Kuraseko Takao
Coe Philip
Sanyo Electric Co,. Ltd.
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