Textiles: fluid treating apparatus – Machines – Single tub and automatic sequential operation mechanism
Reexamination Certificate
1999-03-31
2001-07-10
Coe, Philip R. (Department: 1746)
Textiles: fluid treating apparatus
Machines
Single tub and automatic sequential operation mechanism
C068S012140, C068S012160, C068S023500, C068S023700, C068S902000
Reexamination Certificate
active
06257027
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a full-automatic washing machine comprising a rotatable tub accommodating laundry with water and an agitator disposed in the rotatable tub and agitating the laundry and/or the water, and more particularly to such a full-automatic washing machine provided with two electric motors for driving the rotatable tub and the agitator respectively.
2. Description of the Prior Art
A full-automatic washing machine has conventionally been provided which comprises a rotatable tub provided in an outer tub for rotation and serving both as a wash tub and a dehydration tub and an agitator provided on the bottom of the rotatable tub for rotation. A single electric motor is provided for driving both the rotatable tub and the agitator. When a washing operation is carried out, the rotatable tub is braked to be stopped. In this state, a rotating force of the motor is transmitted via a reduction mechanism to the agitator so that the agitator is rotated alternately clockwise and counterclockwise at relatively low speeds. Further, when a dehydrating operation is carried out, the rotatable tub is released from the braked state, and the rotating force of the motor is transmitted to both the rotatable tub and the agitator without reduction, so that both of them are rotated.
In order that the rotating force of the motor may be transmitted to the rotatable tub and/or the agitator, a clutch mechanism, a reduction mechanism, etc. are required in rotation transmission paths between the motor and the rotatable tub and agitator respectively. These mechanisms complicate the construction of the washing machine and reduce manufacturing and assembling efficiencies of the washing machine. As a result, a manufacturing cost of the washing machine is increased.
Further, errors in a manufacturing accuracy of the clutch mechanism and deterioration with time of the clutch mechanism result in failure in an operation for switching between the rotation transmitting paths. Thus, the conventional full-automatic washing machine has a deficiency in the switching operation of the clutch mechanism. Further, when the washing machine is switched from the washing operation to the dehydrating operation, the switching operation of the clutch mechanism results in noise and the operation of the reduction mechanism also results in noise. Additionally, the switching operation of the clutch mechanism takes a time, resulting in prolongation of a washing time.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a full-automatic washing machine in which without provision of the clutch and reduction mechanisms, the rotatable tub and the agitator can be rotated and stopped independently of each other and their rotational speeds can be controlled independently of each other, whereupon the construction thereof can be simplified.
Another object of the invention is to provide a full-automatic washing machine which can eliminate the switching mechanism conventionally provided in the rotation transmission paths between the drive source and the rotatable tub and agitator and which can improve the reliability of operation without malfunction such as that in switching operation of the clutch mechanism, reduce noise and a washing time.
The present invention provides a full-automatic washing machine comprising a rotatable tub for accommodating laundry together with water, an agitator provided in the rotatable tub for agitating the water or the laundry, a variable-speed washing motor for directly driving the agitator, and a variable-speed dehydrating motor for directly driving the rotatable tub, the dehydrating motor rotating at a higher speed than the washing motor and developing a lower torque than the washing machine.
In the full-automatic washing machine, the agitator is rotated in a wash step including a wash operation with detergent and a rinse operation so that the laundry and water are caused to flow in the rotatable tub. The rotatable tub is rotated in the dehydration step so that washing liquid contained in the laundry is discharged out by centrifugal force. Thus, the full-automatic washing machine includes the agitator and the rotatable tub as rotating members. The agitator has speeds appropriate for washing, whereas the rotatable tub has speeds appropriate for dehydration. In the above-described full-automatic washing machine, the agitator is driven directly by the washing motor and the rotatable tub is driven directly by the dehydrating motor. Accordingly, two independent rotation transmission paths are provided between the drive sources and the rotating members respectively. Further, since the speeds of the washing and dehydrating motors are variable, the motors can be rotated at appropriate speeds respectively. As a result, conventionally required clutch mechanism and reduction mechanism or transmission mechanism are not required. Further, the rotatable tub and the agitator can be rotated and stopped independently, and the speeds of the rotatable tub and the agitator can be controlled independently. These advantages simplify the construction of the full-automatic washing machine, improve the reliability of the operation without malfunction such as that in the switching operation of the clutch mechanism and reduce noise and a washing time.
Furthermore, a large load is applied to the washing motor in the wash step since the agitator is driven to agitate the laundry with a large amount of water. On the other hand, the rotatable tub is rotated at high speeds or spun in the dehydration step. However, the large amount of water as that used in the wash step is previously discharged. Accordingly, a smaller load is applied to the dehydrating motor than to the washing motor. In view of the foregoing, when the dehydrating motor rotates at a higher speed than the washing motor and develops a lower torque than the washing motor, an appropriate washing operation and an appropriate dehydrating operation can be achieved.
In a first preferred form, the washing motor comprises a brushless motor or a switched reluctance motor and the dehydrating motor comprises a brushless motor or a switched reluctance motor. In this construction, the speed of each motor can easily be controlled, and the torque of each motor can be easily be adjusted. Consequently, the required low-speed and high-torque characteristic and high-speed and low-torque characteristic can easily be obtained. Further, an electric brake control can easily be performed. As the result of employment of the electric brake, the construction of the washing machine can further be simplified as compared with the case where a mechanical brake is employed.
In a second preferred form, the washing motor comprises an induction motor and the dehydrating motor comprises a brushless motor or a switched reluctance motor. Brushless motors and switched reluctance motors are suitable for speed control and torque adjustment control. Further, the electric brake control can be performed easily in these motors. In full-automatic washing machines, braking is required for preventing the rotatable tub from rotating with laundry and water in the wash step. This rotation of the rotatable tub with the laundry and water in the wash step reduces the cleaning effect. Thus, the rotatable tub and accordingly the dehydrating motor need to be braked. Since the agitator may be rotated with the rotatable tub in the dehydration step, the washing motor need not be braked. In view of this, the washing motor may comprise an induction motor. Further, both the washing and dehydrating motors may be constructed into a radial gap type. As a result, high-torque motors can be obtained as the washing and dehydrating motors and are suitable for full-automatic washing machines ranging between a large capacity and a small capacity. Further, both the washing and dehydrating motors may be constructed into an axial gap type. In this case, the vertical dimension and the weight of the washing machine can be reduced. These motors are suita
Coe Philip R.
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
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