Patent GB-1035725-A (GB)
Title: Improvements in or relating to motor drive and needle positioning mechanisms of sewing machines
IPC: D05B69/22
Filed: 1964-08-14
Abstract: 1,035,725. Clutch control. G. M. PFAFF A.G. Aug. 14,1964 [Aug. 16, 1963], No.33384/64. Headings F2C and F2L. [Also in Divisions D1 and H2] In a sewing machine having an auxiliary reduced-speed drive for stopping the machine with the needle in either a raised or a lowered position, a change-over switch for selecting said position is controlled by movement of a pedal, lever or the like means in one or the other direction from its rest or normal position. A driving motor 1, coupled to the main shaft 107 of a sewing machine 105 by a belt 106, comprises a rotor 10 carried by a hollow shaft 11, one end of which carries a clutch disc 12 and the other end of which carries a sleeve 16 which is formed with a gear 15 and which journals a clutch disc 17. The latter is formed with a gear 27 coupled by reduction gearing (not shown) to gear 15, and carries a friction ring 28. A shaft 31, journalled in shaft 11, carries a clutch disc 29 adjacent disc 17. A fixed hub 32 slidably supports a sleeve 33 journalling a shaft 63 which carries at one end a pulley 64 driving belt 106, and at the other end a clutch disc 66 carrying on its respective faces friction rings 67, 68. Shaft 61 projects slidably into the hollow inner end of shaft 63, is keyed thereto by a pin-and-slot connection 94, 95, and abuts a spring 93 to bias shaft 63 outwardly for engaging friction ring 68 with a braking disc 70 journalled on a shoulder 69 of hub 32. An annular groove 80, formed in disc 70, is loosely engaged by a pair of pins 79 projecting from a braking ring 73. A radial extension 74 of ring 73 is formed with a notch 75 engaging a fixed pin 76. A diametricallyopposed extension 78 engages a slot 81 in a lever 82 pivoted on a fixed pin 83. One arm of a torsion spring 87, mounted on a fixed bolt 86, abuts on a fixed pin 88, and the other arm abuts the outer end 85 of lever 82, whereby ring 73 is pivoted on pin 76 to engage the pins 79 with the sides of groove 80 for locking disc 70. Levers 36, 37 are pivoted to the respective ends of a fixed pin 35. The lower end of lever 36 passes between a pair of stop lugs 39, 40 on lever 37, and is connected by a link 109 to a treadle 108. The upper ends of levers 36, 37 carry respective pins engaging respective slots in a bar 43 pivoted on a pin 44 which passes through a slot 45 in hub 32 and is fixed to sleeve 33. One end of bar 43 carries a normally-closed micro-switch 46, and the other end carries a change-over micro-switch 47. A bar 50 is pivoted at one end to bar 43, is formed intermediately with a clearance notch for pin 44, and carries at its other end a cam lug adjacent switch 47. A non-rotatable bar 54, engaged by pin 44 and slidably engaging a fixed pin 58, carries at one end a cam lug adjacent switch 46, and has at said end a loose pin-andslot connection with bar 50. A compression spring 60 is disposed between a fixed depending arm 34 and respective shoulders on the levers 36, 37 to bias the latter clockwise and to position bar 43 outwardly and at right angles to shaft 63. A lever 96 is connected to the armature of a fixed solenoid 103, and is also connected to one end of a slidable rod 100, the tapered other end 104 of which is disposed between a pair of lugs 92 on the inner end of lever 82. To start the machine, treadle 108 is depressed, when lever 36 initially turns bar 43 clockwise, whereby the cam lug on bar 54 opens switch 46. After lever 36 engages lug 40, bar 43 is moved bodily inwards, whereby sleeve 33, engaging disc 66, moves the latter inwardly to engage ring 67 with disc 12 for driving the sewing machine. When treadle 108 is released, ring 68 re-engages disc 70 to stop the sewing machine until bar 43 resumes its normal position to close switch 46 for energizing solenoid 103. Lever 96 then actuates rod 100, whereby end 104 engages a lug 92 to pivot lever 82 and thereby free pins 79 from slot 80, and also actuates shaft 31 to engage disc 29 with ring 28, whereby shaft 63 and ring 70 are driven slowly until an insulating segment 120 on a disc 118 fast with shaft 107 engages a brush 116 to stop the machine with the needle lowered. If the treadle is now raised, bars 43 and 50 are turned counter-clockwise, but bar 50 turns faster than bar 43, whereby the cam lug on bar 50 actuates switch 47 for energizing solenoid 103 via a brush 117. Shaft 107 is then driven slowly through 180 degrees until segment 120 engages brush 117 to stop the machine with the needle raised. In a modification, Fig. 7 (not shown), a single lever 141 is pivoted to a downward extension 139 of an outer slidable sleeve 133 supporting an inner slidable sleeve 136 journalling shaft 63. Pins projecting from sleeve 136 pass through slots in sleeve 133 into loose engagement with the slotted upper end of lever 141. The switches 46, 47 are mounted on extension 139, and are actuated by respective movements of lever 141 in one or the other direction from its normal position.