Patent GB-824505-A (GB)
Title: Improvements in or relating to driving means for a sewing machine
IPC: D05B69/22
Filed: 1957-05-20
Abstract: 824,505. Gearing for stopping machinery; change-speed gear. GERBAUD, A. H. May 20, 1957 [May 25, 1956], No. 19544/57. Class 80 (2). [Also in Groups VII, XXXV and XXXVII] An electric motor for driving a sewing machine is provided within its casing 1 with a friction driving clutch and change-speed gearing. A hollow spindle 13 is fixedly mounted in an end wall 8 of the casing. A rotary shaft 14 is slidably mounted in spindle 13 and is biased to the left by a spring 16. A rotor 17 is journalled on spindle 13 via ball bearings 20, 24. A stator 27, which is also journalled on spindle 13, is separated from bearing 24 by a ball bearing 28 and carries on the end a cam ring 29 which opposes a cam ring 33. Balls 31 are interposed between said rings and are normally accommodated in opposed recesses therein. Ring 33 is connected by bars 34, slidable in splines 35 formed in spindle 13, to a ring 37, and the latter is connected by rods 38, slidable in wall 8, to a ring 40 which carries a cam ring 42 opposing a cam ring 45. Balls 46 are interposed between rings 42, 45 and are normally accommodated in opposed recesses therein. A lever 48, pivoted on shaft 14, is keyed to ring 45. Gear teeth 55, formed on the rotor, mesh with a gear 56a carried by a shaft 57 journalled in a structure 58 fixed to the spindle 13. A shaft 60, also journalled in structure 58, is connected to shaft 57 by gears 61, 61a, and is connected by a gear 61 with a gear 62 journalled, via a ball bearing 73, on spindle 13. Gear 62, which is thereby driven at reduced speed, is coupled by a sleeve 63 and a freewheel 72 to a ring 68. A ring 66 is slidably mounted on ring 68 via pins 67, and is spring-biased into engagement with a friction lining 65 on a ring 64 fixed to a sleeve 63. A friction lining 69 on ring 66 is normally spaced from a ring 70 fixed to the rotor. A sleeve 75, journalled on shaft 14 via ball bearings 74, 76, carries at one end a driving pulley 80 and at the other end a ring 77 provided with a brake lining 79 normally engaged with the rotor casing 1, and also provided with a clutch lining 78 normally spaced from ring 66. Lever 48 is so coupled to the machine-controlling pedal that when the latter is partly depressed the balls 46 partly emerge from their recesses and shaft 14 is moved sufficiently rightwards to engage lining 78 with ring 66 for driving the machine slowly. When the pedal is fully depressed the balls completely emerge, whereby shaft 14 again moves rightwards, when lining 78 shifts ring 66 clear of packing 65 and carries packing 69 into engagement with ring 70, to drive the machine at full speed. When the pedal is released, spring 16 shifts shaft 14 leftwards to engage packing 79 with the motor casing to stop the machine. The pedal, on release, is arranged to close a switch for energizing a solenoid, whereby the stator windings are reversely energized through resistances. The stator then moves angularly in the contrary direction to the rotor, whereby the balls 31 are forced out of their recesses in the rings 29, 33. Ring 33 is thus forced rightwards and shaft 14 moves therewith sufficiently to engage packing 78 with ring 66 for again driving the machine slowly, until one or the other selected one of a pair of switches associated with the uppermost and lowermost positions respectively of the needle opens to de-energize the solenoid to stop the machine. In a modification the stator is fixed rigidly to the spindle 13. A solenoid incorporated in the motor is adapted, when the sewing machine stops, to couple a cam ring, corresponding to ring 29, with the rotor. Shaft 14 is thereby shifted to the right to drive the sewing machine at slow speed until the latter is stopped with its needle in either the uppermost or lowermost position.