GB1275968A - Washing machine - Google Patents

Abstract

1275968 Washing machines HITACHI Ltd 22 Oct 1969 [23 Oct 1968] 51865/69 Heading D1A A washing machine comprises a drum 14 supported elastically from an outer frame 2, means for driving the drum at three different stepped speeds, means 49 for detecting vibration of the drum only when the drum is driven at its intermediate speed and means, when the vibration detected remains below an allowable value for a preset time, for accelerating the drum and rendering the means 49 inoperative. The drum is driven at a washing speed or the intermediate speed by a pole change electric motor 28 through a pulley 32, clutch 31 and pulleys 33 and 16, and at a spin speed by a motor 29 driving the pulley 33 directly. Friction damping is provided by plates 37 secured to the tub 8 and engaged by friction members 40, 41 attached to the base of the frame. The vibration detector includes a mercury switch (Fig. 3, not shown) mounted with its axis at 15‹ to the horizontal so that its natural frequency is equal to or just above the intermediate speed which is chosen between the speed at which laundry is held against the inside surface of the drum and a speed between the critical speeds of the drum for horizontal and vertical vibrations. The control means includes a door switch 63, a pressure switch 45, a series of cam switches 64-68 driven by a timer 69 and an auxiliary timer 77. In operation the pressure switch 45, which is sensitive to the tub water level, is successively connected to an electromagnetic filling valve 43 to fill the tub and to the timer motor 69 to start the washing operation which proceeds with the motor 28 in its multipole condition rotating the drum 14 at 50 rpm followed by a draining period and a rinsing period. Then the cam switch 66 moves from contact b to contact a and the cam switch 67 closes operating the motor 28 at its low speed and starting the auxiliary timer 77 which closes a contact 84 causing the motor 28 to be shifted to its small pole number condition thereby accelerating the drum to 100 rpm. Should the vibration detector be actuated the drum is rotated at 50 rpm again to redistribute the clothes before the timer 77 again closes the contact 84. If the vibration detector is not actuated during the preset time a contact 85 is closed disconnecting the motor 28 and detector 49 and energising the spin motor 29 to rotate the drum 14 at 700 rpm.