| 摘要 |
1426002 Motor controllers; centrifugal switches SCOVILL MFG CO 27 June 1973 [3 July 1972] 03850/74 Divided out of 1426001 Heading H1N A kitchen mixer having a housing 12, 14, an electric motor 26 in the housing and having a drive-shaft 28 terminating in a worm gear 38, worm-wheels 40, 42 engaging either side of the worm gear 38 and each having a downward hub mounted in the housing for rotation, the hubs each drivingly receiving the upper ends of respective mixer blades (not shown), one of the worm-wheels supporting a rotary surface carrying a conductive element 96 for rotation therewith, the housing also mounting conductive brush means 82 adapted to engage the element 96, means for manually moving brush 82 in a path of traverse along element 96, a power line to the motor 26 being interrupted with one end connected to brush means 82 and the other end connected to the conductive element 96 which is irregular in shape so that as the element rotates the brush 82 is in contact with it a greater proportion of the time as the brush approaches one end of its path of traverse, whereby the speed of the motor may be varied by moving the brush 82. As shown, the means for manually moving brush 82 comprises a knob 18 geared at 24 to a toothed sector plate 50 carrying the brush 82. The rotary surface is preferably a disc 90 with a star-shaped element 96 continuously engaged by wiper 104b, but may comprise a drum with a suitably configured conductive insert on its periphery. To avoid stalling of the motor at low speeds and difficulty in starting if brush 82 is not in contact with element 96 when it is at rest, a centrifugal switch interconnects the brush 82 and element 96 below a given slow speed. This switch comprises an arm 124 (Fig. 4) carried on a metal post 94 extending up from element 96 and a ring element 102 connected to brush 82 via sector plate 50. When the motor is running above a given slow speed the arm 124 lifts (as shown by broken lines) and the brush 82 is then effective as a speed controller. |
