GB1270131A - Improvements in or relating to electric motor assemblies - Google Patents

Abstract

1,270,131. Oscillating machines. BRAUN A.G. 23 July, 1969 [26 July, 1969], No. 36962/69. Heading H2A. In a motor, e.g. of a dry shaver, having a pendulum-type armature and adapted for use at two or more supply frequencies, the natural frequency of the oscillatory system is adjustable by additional mass(es) which can be secured to or released from the oscillatory system. Figs. 1, 3 show a dry shaver for use on 50 or 60 Hz supplies, comprising a casing 1 enclosing a motor having stator poles 13, 14 and coils 15, 16 mounted on a plate 11. The armature 18 is pivoted about a pin 17 and drives the shaver cutting head 6. Springs 19, 20 extend between the armature and fixed abutments 21, 22, the abutment 21 being adjustable. A pair of arms 31, 32 having cylindrical end portions 33, 34 (also Fig. 5, not shown) are also separately pivoted about pin 17, these arms constituting the additional masses. Between the two arms 31, 32 is provided a cam 43 fixed to a rotatable disc 42 (see Fig. 5). When the cam is in its upper position, as in Fig. 3, it forces the two arms away from the armature so that they do not oscillate with it. When the cam is in its lower position, however, as in Fig. 1, it does not engage the arms which are therefore urged, under the action of a spring 35, against the armature so as to oscillate with it. The cam is coupled to an adjusting knob accessible from outside the casing, and may also be coupled to a voltage selector to enable voltage and frequency to be selected together.