GB1282153A - A sewing machine - Google Patents

Abstract

1282153 Sewing machine driving BROTHER KOGYO KK 18 Sept 1969 [21 Sept 1968] 46150/69 Heading DIG A sewing machine comprises a needle 13, a pressor foot 14, operating means 67, 68 for controlling the lifting and lowering of the presser foot, power transmitting means 16 for driving the needle and including a clutch 40, 41, 47, a treadle 24 for engaging the clutch to drive the needle, a needle positioner 32 and an electric control means, for controlling the operating means and the needle positioner, energised through a switch 33 operable in response to release of the treadle, the control means including a timer providing a time delay between release of the pedal and lifting of the presser foot to cause the lifting after the needle has been stopped at a predetermined position. The control means comprise an electrical circuit Fig. 7 depicted in several conditions in Figs. 8-15, (not shown) which includes relays R2 and R3 having contacts r21, r31 in series with a coil 70 of an electromagnetic valve 68 controlling the raising of the presser foot. Starting, presser foot raising and lowering Preparatory to sewing lines 90, 93, 99 and 100 are energised with high speed motor 16 rotating, coil 70 is energised through normally closed contacts r21, r22, to raise the presser foot below which the work is then positioned. When the pedal is partially depressed switch 33 opens and the foot is lowered. Further depression of the pedal actuates the clutch to cause the high speed motor 16 to drive the machine. Stopping at lower position, presser foot raising When the treadle is released switch 33 closes and relay R3 is energised through the N.C. contact r12 and the 'needle down' contact 84s of the needle positioner thereby closing N.O. contacts r32 and r34 and opening N.C. contacts r31 r33. Low speed motor 17a now runs and is engaged with the machine to drive it at low speed. Relay R2 is connected in series with capacitor 95 and is thus excited only for as long as is required to stop the machine at the lower position, N.C. contact r21 opening meanwhile. When the positioner has rotated to open contact 84s relay R3 is de-energised, contacts r32 and r34 opening and contacts r31 and r33 closing. Relay R5 is held on momentarily by capacitor 98 to maintain contact r51 momentarily closed to provide field excitation and dynamic braking by the shorted armature circuit of 17a. R2 is excited by charging current through capacitor 95, so the foot remains lowered until, with the machine stopped and capacitor 95 charged, contacts r21 close to energise coil 70 and raise the foot. Stopping at needle raised position, thread cutting. Operation of a knee lever 19 by the operator closes switch 20 to energise relay R1 and be held on by its contacts r11. N.C. contacts r12 open and N.O. contacts r13 close. Relay R3 is excited through the 'needle up' contact 83s and relay R5 is excited. The low speed motor now drives the machine. As contacts 81s close relay R4 is excited and coil 78 is energised to actuate pneumatic mechanism to cause thread cutter blade 74 to rotate and catch the thread.