Textiles: fluid treating apparatus – Machines – Combined
Reexamination Certificate
2000-03-27
2001-12-25
Stinson, Frankie L. (Department: 1746)
Textiles: fluid treating apparatus
Machines
Combined
C068S012020, C068S133000
Reexamination Certificate
active
06332343
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an automatic washing machine, and more particularly to an improvement in a power transmission mechanism for transmitting torque developed by an electric motor to a rotating tub and an agitator in such an automatic washing machine.
2. Description of the Prior Art
An automatic washing machine having a dehydrating function comprises a rotating tub serving both as a washing tub and as a dehydrating tub and an agitator mounted on a bottom of the rotating tub. Torque developed by a drive motor is transmitted only to the agitator in a wash step, whereas the motor torque is transmitted both to the agitator and to the rotating tub in a dehydration step. Japanese Patent Application Publication No. 10-52595 (1998) discloses one of power transmission mechanisms transmitting the motor torque selectively only to the agitator or both to the agitator and to the rotating tub.
In the transmission mechanism disclosed by the above mentioned publication, the rotating tub is rotated via a hollow dehydration shaft, and the agitator is rotated via a wash shaft extending through the dehydration shaft. A vertically movable connecting gear mechanism or clutch is provided for connecting the dehydration and wash shafts to each other and disconnecting the shafts from each other. The connecting gear mechanism is vertically moved via a number of parts including rotating gears, lifting gears, a lifting ring, a lifting guide plate, etc. These parts complicates the construction of the connecting gear mechanism.
On the other hand, Japanese Utility Model Publication No. 6-42630 (1994) discloses another transmission mechanism comprising a hollow dehydration shaft provided for rotating the rotating tub and a wash shaft extending through the dehydration shaft and provided for rotating the agitator via a reduction gear mechanism. The wash shaft has a lower end connected to a boss of a pulley to which the motor torque is transmitted. A lower end of the dehydration shaft has a guide groove formed in an outer circumferential face thereof. The boss of the pulley also has an upper end with a guide groove formed in an outer circumferential face thereof. A cylindrical cap (clutch) is provided so as to be vertically moved along the guide grooves. The cap is vertically moved by a lever.
In the aforesaid construction, however, a large torque is transmitted from the boss via the cap to the dehydration shaft. Accordingly, when the cap, boss and dehydration shaft have respective portions which engage the guide grooves and have small vertical dimensions respectively, an inner circumferential surface of the cap is subjected to an excessive force such that the cap is deformed or broken. As a result, the portion of the cap engaging the guide grooves needs to have a large vertical dimension, whereupon the size of the overall cap is increased vertically, and an amount of vertical movement of the cap is increased. Consequently, the size of the transmission mechanism is increased.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an automatic washing machine in which the power transmission mechanism for transmitting the motor torque to the rotating tub and the agitator has a simple construction and in which a switching portion of the transmission mechanism has a small height.
The present invention a washing machine comprising a water tub having a bottom with a through hole, a rotating tub rotatably provided in the water tub, an electric motor including a rotor and provided on an underside of the water tub, a hollow tub shaft rotatably mounted on the bottom of the water tub so as to extend through the hole of the water tub, the tub shaft having an upper end connected to the rotating tub and a lower end with an outer circumferential face formed with a sliding guide, a boss provided on a central portion of the rotor so as to be located below the tub shaft, the boss including an upper portion formed with an annular coupling portion having a diameter larger than a diameter of the tub shaft, an agitator shaft rotatably provided inside the tub shaft and having an upper end connected to the agitator and a lower end connected to the boss, a cylindrical clutch having an inner circumferential face formed with an annular engaging portion engaging the sliding guide, the clutch being fitted with the lower end of the tub shaft so as to be moved vertically along the sliding guide between predetermined upper and lower positions, the clutch being coupled to the coupling portion of the boss when assuming the lower position, the clutch being released from coupling with the coupling portion of the boss when assuming the upper position, and a lift for moving the clutch vertically.
According to the above-described construction, the clutch is released from the coupling to the coupling portion of the boss when assuming the upper position. Accordingly, torque developed by the motor is transmitted only to the agitator shaft. When assuming the lower position, the clutch is coupled to the coupling portion of the boss, so that the motor torque is transmitted both to the tub shaft and to the agitator shaft. Consequently, the transmission path of the motor torque can easily be switched by a simple construction in which the clutch is vertically moved by the lift. Further, the coupling portion of the boss has a larger diameter than the tub shaft. Accordingly, even when a vertical dimension of the portion of the clutch connected to the coupling portion of the boss is reduced, the clutch is prevented from being subjected to an excessive force when the motor torque is transmitted from the boss to the tub shaft. Consequently, the vertical dimension of the clutch can be reduced.
The boss preferably has an upper end on which an upwardly extending cylindrical portion is provided, the cylindrical portion having an inner circumferential face formed with a plurality of inner teeth constituting the connecting portion. In this case, the clutch has a lower outer circumferential portion formed with an outer teeth engaging the inner teeth. In this construction, the engaging portion of the clutch engaging the sliding guide and the outer tooth coupled to the coupling portion are separately disposed on the inner and outer circumferential portions of the clutch respectively. Consequently, since the engaging portion and the outer tooth can vertically be overlapped, sufficient vertical dimensions can be ensured for the engaging portion and the outer teeth respectively even when the clutch has a reduced vertical dimension.
The washing machine preferably further comprises a flange formed on the upper end of the clutch and having an outer circumferential end, a fitting portion provided on the outer circumferential end of the flange and having a plurality of fitting teeth, and a co-rotation preventing portion provided on an underside of the water tub and including a plurality of co-rotation preventing teeth. In this construction, when the clutch assumes the upper position, the fitting teeth of the fitting portion engage the co-rotation preventing teeth of the co-rotation preventing portion so that rotation of the clutch is disallowed. As the result of the construction, rotation of the tub shaft, that is, rotation of the rotating tub can reliably be prevented when the agitator shaft is rotated by the motor.
The washing machine preferably further comprises a bearing provided on the bottom of the water tub for supporting the tub shaft. In this case, the co-rotation preventing portion is disposed around the bearing. Further, when the clutch assumes a middle position between the upper and lower positions, a part of the clutch is coupled to the coupling portion of the boss and a part of the fitting portion of the clutch is engaged with the co-rotation preventing portion. Consequently, the clutch is rotated when assuming the middle position, whereupon the teeth of the fitting portion can correctly engage the teeth of the co-rotation preventing portion respectively.
Each fitting tooth has
Koketsu Tadaaki
Kono Tetsuyuki
Noguchi Hiroyuki
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
Stinson Frankie L.
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