Patent GB-1513084-A (GB)
Title: Sewing machines
IPC: D05B69/22
Filed: 1976-03-29
Abstract: 1513084 Intermittent stitching sewing machine JANOME SEWING MACHINE CO Ltd 29 March 1976 [27 March 1975] 12607/76 Heading DIG A sewing machine having an intermittent drive comprises a housing, an upper shaft 6 journalled in the housing, a belt wheel 5 mounted on the upper shaft and rotatable relative thereto, clutch means actuable to connect or disconnect the belt wheel and upper shaft, means for actuating the clutch, stop means for engaging the actuating means to actuate the clutch, cam means 46 for releasing the actuating means and pawl means 48 for operating the releasing means. The belt wheel 5, which is rotatable on a collar 8 secured to shaft 6, carries pawls 11 having projections 52 engageable, as described below, in recesses 50, 57<SP>1</SP> in a releasing cam member 46 and a pawl wheel 37. The clutch means comprises a roller 18 disposed in a tapering passage formed between the bore face 17 of wheel 5 and a plate 15 on member 8, the roller 18 being disposed in a slot 21 in a tongue 20 extending from a stop member 19 having cushioned slots 28, 29 receiving stepped pins 60, 61 screwed into collar 8. Member 19 thus has limited movement about the axis of the shaft and is biassed in a clockwise direction, (Fig. 7), by spring 41. The releasing cam member 46 is mounted on face 25 of stop member 19 with rotatable freedom limited by the engagement of projection 55 within an arcuate slot 27, a spring 26 biassing the member 46 counter clockwise. Cam member 46 is retained on member 19 by a pawl wheel 37 having recesses 571 separated by cam faces 57, recesses 50 in cam member 46 being either masked by faces 57 or matched by recesses 57<SP>1</SP> according to the relative position of member 46 as located by spring 26 or by the abutment of a cam stop 24 on member 46 with the arm 75 of a releasing stop member 48 positioned by linkage 79, 81, 83, 85, 87, 90 connected to an operating knob 91 of an electrical switch 93 having 'slow' contacts b, c, d and 'fast' contacts b, a connected to the driving motor circuit. Operation. For high speed sewing knob 91 is in its upper position connecting contacts a, b, the linkage rotating releasing stop member 48 to a position clear of the path of stop 24. Spring 41 can urge releasing cam member 19 in a direction to position roller 18 in the narrow end of the passage and wheel 5 drives the shaft 6. Cam faces 57 on wheel 37 mask the recesses 50 on member 46. A similar condition, but with the motor driving at a lower speed, prevails when the switch convects b and c. In the lowest position of switch 19 the motor runs at the lower speed and end 75 of lever 48 can engage both the stop 24 on member 19 and a projection 49 on the releasing cam member 46, when the foot control, (101 Fig. 1 not shown), is operated until projection 49 abuts 75 to stop the cam member 46 stop member 19 continues to rotate unmasking recess 50, until stop 24 reaches 75, which releases the clutch action of roller 18 and shaft 6 stops, the cushions in slots 28, 29 absorbing the impact. As wheel 5 is rotating centrifugal force maintains pawls 11 away from the recesses 50. On release of the foot control the wheel 5 stops, one pawl dropping into a recess 50, 57<SP>1</SP>. In a modification (Fig. 19 not shown) a spring (108) is provided to assist this action. On reoperation of the foot control wheel 5 rotates, its pawl 11 in recesses 50, 571 rotating the releasing cam member 46, stop 49 thereon deflecting end 75 of lever 48 against the action of spring 78 to disengage the lever 48 from the shoulder 23 of stop member 19. The latter is then rotated by spring 41, which was wound a little on stopping, to engage roller 18 of the clutch with the narrow end of the recess to connect the shaft 6 to the wheel 5 for rotation therewith through one revolution before lever end 75 again abuts shoulder 23 to stop the shaft after one busting stitch. Repeated release and depression of the foot lever causes successive single busting stitches. Bobbin winding (Fig. 5). The device comprises a rubber rimmed wheel 105 journalled on an arm 103 of a toggle lever 97 provided with an overcentre spring 102 which urges the lever either into a position (shown) with wheel 105 away from a ribbed face 106 on pulley 5 or to a position in which the rubber rim abuts the ribbed face. When the lever 97 is mannally moved to the latter position its second arm 101 moves a lever 95 to place an arm 96 in a position to abut stop 24 of member 19. in place of lever end 75 which is withdrawn when knob 91 is moved upwards for high speed running. This abutment action release clutch 18, 19, and shaft 6 does not rotate while pulley 5 and wheel 105 rotate for bobbin winding. Handwheel. The handwheel 69 is releasably engaged by arms 64, 65 on a retainer 63 secured to collar 8 on shaft 6 by screws 66, 67. A hole 72 in the handwheel boss receives the head 73 of the screw 66 to rotationally connect the handwheel to shaft 6.