Patent GB-622115-A (GB)
Title: Improvements in or relating to rotary mixers driven by electric power
IPC: A47J43/046
Filed: 1946-05-28
Abstract: 622,115. Mixing machines. GENERAL MILLS, Inc. May 28, 1946, No. 16155. Convention date, Sept. 18, 1945. [Class 86] [Also in Group XXXV] An electric power driven rotary mixer comprises a mixing receptacle having a rotary agitator therein operatively connected with a removably mounted magnetically responsive rotary element and adapted to be driven by electrically operated magnetic driving means arranged externally of the receptacle, the latter being provided either with a non-magnetic wall area adjacent the rotary agitator and. its driving element or with a hollow base unit in which the rotary element is disposed, said unit having an electric heater surrounding said element for heating the receptacle. A mixing vessel 20, Fig. 1, has a base 20<SP>1</SP> of non-magnetic stainless steel having a depending well portion 37 for holding a casing 31 containing a rotary permanent magnet member 40, Fig. 6. Power for driving the latter is transmitted magnetically from a ring-shaped permanent magnet member 41 disposed around the well 37 and rotated by an electric motor 43. A stirrer, having arms 23 connected by upstanding portions 28, or by a central tube, to a cap 35 on a shaft 32, is rotated by the member 40 through a reduction gearing comprising pinions 46, 49, 50, 48. Upwardly projecting portions 24, 25 of the arms 23 are angularly disposed so as to drive the material being mixed inwardly, and the leading edges of the arms are bevelled to facilitate removal of material adhering to the base of the bowl 20. The casing 31 together with the driving gear enclosed therein and the stirrer are detachable as a single unit; and the bowl 20 is detachable and may be supported by its base flange 21. The machine further comprises an electric heating coil 52 which may be controlled manually by a rheostat 58 and which may be switched on and off independently of the motor 43, the speed of which may be controlled manually by a rheostat 57. In an alternative construction the base of the mixing bowl is not provided with a depending well, and the driving magnetos are disposed on each side of the base with their pole faces parallel thereto. In a further alternative construction a pair of stirring members 97, 98. Fig. 12, are rotated in opposite directions through pinions 108, 109 driven by a pinion 107 rigid with a rotary magnet member 103 actuated by a surrounding magnet member 104 driven by an electric motor 105. In a further modified construction the driving magnet member of the magnetic coupling together with its driving motor are replaced by an electric motor stator 132, Fig. 16, which directly actuates a motor rotor disposed within a housing 130 in a well 131 in the base of the mixing bowl 120. The stator 132 comprises upwardly facing poles 135, and the driving coupling between the rotor and the stator is improved by the provision of separable magnetic extension pieces for the poles 135 in the form of inserts 148, 149, secured respectively, in the base of the well 131 and in the base of the housing 130. An electrically controlled timing mechanism may be provided for terminating the operation of the agitator after a predetermined period and such mechanism may also control the period of operation of the beating means.