GB1255470A - Improvements in or relating to washing machines - Google Patents

Abstract

1,255,470. Washing machines. PHILIPS GLOEILAMPENFABRIEKEN N.V. 20 May, 1970 [23 May, 1969], No. 24467/70. Heading D1A. In a method of using a washing and spin drying machine comprising a resiliently mounted tub accommodating a drum which is rotatable about a horizontal spindle, an electric motor for driving the drum at a washing speed and at a spin drying speed, a constant ratio transmission between the motor and the drum spindle, and water supply and drain means, after the washing operation (e.g. 50 r.p.m.) when the motor is changed over to the spin drying speed and the drum is accelerated with the tub still full of water an intermediate speed (e.g. 70 r.p.m.) is attained at which the torque delivered to the spindle and the. reaction torque are balanced until the water in the tub has been driven into rotation when the reaction torque is reduced and the drum acceleration continues. The drum accelerates through the critical speed range of 100 to 160 rpm to a second intermediate speed (e.g. 200 to 300 r.p.m.) when the drum may be balanced by introducing water into chambers secured to the drum. On draining of the water within the drum, the drum accelerates finally to the spin drying speed (e.g. 1000 r.p.m.). Although the pump may be switched on at the beginning of the spin drying cycle or when either of the intermediate speeds is attained, due to a time lag in its effective operation, the tub is not drained before the second intermediate speed is attained. As shown the tub is suspended by helical springs and is provided with dampers. The motor may be an AC motor with two windings or may be a permanent-magnet induction direct current motor fed by an electronic speed control device. The latter motor may be connected in series with a heater for the tub and braking may be effected by causing the motor to act as a generator for the heater.