| 摘要 |
1,156,851. Sewing machines. UNION SPECIAL MACHINE CO. 25 July, 1966 [26 July, 1965], No. 33314/66. Heading D1G. An arrangement for staffing the drive of a sewing machine with the needle in a preselected position comprises an electric motor 16 which drives a flywheel 24 through a shaft 28, journalled in an axially-slideable bearing 30, which carries at one end a clutch member 32 and at the other end a pulley 38 coupled by a belt 14 to the arm shaft of the sewing machine 2. Bearing 30 is coupled to one arm of a lever 48, the other arm of which is connected by a rod 52 to a treadle 54. Depression of the latter thereby shifts hearing 30 to engage clutch member 32 with flywheel 24 for driving the sewing machine. On release of treadle 54, clutch member 32 retracts from flywheel 24, but is prevented from engaging a conventional brake plate 40 by engagement of lever 48 with a stop 98. Shaft 28 has an extension 88 carrying a pulley 90 coupled by a belt 92 to a pulley 70 of an auxiliary motor 60 which during normal operation of the machine is not energised but is driven by the main motor 16 and the shaft of which is journalled in a bearing 80 containing a unidirectional brake. A fixed cylindrical casing 102, contains a lamp which illuminates the face of a flywheel 12 on the machine arm shaft. A strip (130), mounted radially on flywheel 12, is adapted to reflect light alternately on to photocells (112) (120) mounted diametrically in casing 102 at positions corresponding to raised and lowered positions respectively of the needle 10. When treadle 54 is depressed to engage clutch member 32, switches 94 and 95 are actuated, while shaft 28 rotates at 3450 r.p.m. to drive flywheel 12 at 5500 r.p.m. and motor 60 at 8000 r.p.m. Switch 94 connects a capacitor (208) in circuit for charging, while switch 95 connects a resistance (216) across a capacitor (232) and relay coil (230) to deenergise the latter. When treadle 54 is released to disengage clutch member 32, switch 94 connects capacitor (208) across a relay coil (220), whereby motor 60 is energised and, by running at 1725 r.p.m. reduces the speed of flywheel 12 to 1200 r.p.m. Switch 95 disconnects resistance (216), whereby, after a time delay, coil (230) closes a switch (234) to connect in circuit that one of the photocells (112) (120) selected by a switch 75 and corresponding to "up" and "down" positions of the needle respectively. When the selected photocell is illuminated by strip (130), a relay coil (240) is energised for actuating a switch (242) to connect a charged capacitor (206) across a relay coil (244), whereby the direction of energisation of motor 60 is reversed, causing the motor to act as a brake, and the machine thereby stops in the selected position. If a treadle 150 is depressed, when treadle 54 is released, switches 153, 154, 155 are actuated. Switch 153 energises a capacitor (308), switch 154 opens the circuit through switch 75 and the selected photocell to de-energise coil (240), and switch 155 charges capacitor (208) and energises coil (220) to switch in motor 60 which thereby drives the machine at low speed as long as treadle 150 is depressed. On release of treadle 150, charged capacitor (306) discharges through a coil (308) to close a switch (310) for connecting a resistance (320) across coil (220) to reduce the discharge time of capacitor (208), and the selected photocell is connected in circuit. For making a single stitch, treadle 150 is depressed momentarily. |
