Patent GB-871668-A (GB)
Title: Improvements in and relating to the synchronisation of endless conveyors
IPC: B65G23/00
Filed: 1959-07-15
Abstract: 871,668. Endless conveyers. SYLVANIA ELECTRIC PRODUCTS Inc. July 15, 1959 [July 22, 1958], No. 24385/59. Class 78 (1). [Also in Group XXIV] A first conveyer comprising a pair of endless chains 23 having article carriers 27 and driven through variablespeed belt gearing 24, 26 from a motor 22, is maintained in synchronism with a second conveyer comprising a pair of endless chains 13 having article carriers 25 from which articles are to be transferred to the carriers 27 and which chains are driven from a separate motor 12 at a fixed speed, by control means adapted to sense a difference in the speeds of the two pairs of chains and to vary the ratio of the gearing 24, 26 in such manner that the chains 23 are alternately accelerated and decelerated about the speed of chains 13 by decreasing amounts until the speeds are matched. The control means comprises a differential gear 34 having input shafts 36, 38 which are respectively connected by chain gearing 44, 46 to the sprocket shafts 18, 30 of the conveyer chains 13, 23, the arrangement being such that when the speeds of the chains 13, 23 are equal the shafts 36, 38 rotate at the same speed. The shaft 36 carries an internallytoothed gear 104 which drives a sun-wheel 112 loosely carried on shaft 36 through planet gears 106, 108 carried by an arm 110 pivotally mounted on shaft 36. Shaft 38 is coupled to a gear-wheel 130 through an overload release clutch comprising balls 126 urged radially outwardly by a spring 124 into recesses (not'shown) in the circumferential face of a cavity in the gear-wheel 130. Gear-wheel 130 has the same number of teeth as the internally-toothed gear 104, and engages the sun-wheel 112, so that the arm 110 remains stationary when shafts 36, 38 are driven at the same speed. If the speed of one of the conveyers varies, arm 110 is moved within limits determined by stops 136, 138 and operates one or other of two micro-switches 152, 170 through operating levers 146, 164 and operating arms 140, 160, respectively, to cause energization in one or other direction of rotation of a motor 48 which through screw-and-nut mechanism shifts the motor 22 so that pulley 24 expands or contracts to vary the ratio of the gearing 24, 26 such as to tend to restore synchronism. The result is that hunting of the arm 110 occurs causing the speed of chains 23 to be varied about that of chains 13 by decreasing amounts until the speeds are again matched and arm 110 remains horizontal. In order to limit hunting of arm 110 the operating arms 140, 160 are connected by stiff pivots to the arm 110 so that after operating the respective micro-switch each arm can pivot through a roller 142 on its upper end rolling along the respective lever 146 or 164. Resetting blocks 143, 145 return the arms to vertical positions during subsequent downward movement. Should the speed difference be so large that arm 110 engages one of the stops 136, 138 the balls 126 of the overload release clutch leave the recesses and subsequently re-engage in another pair of recesses when the speeds have been more nearly matched. The spacing of the recesses in the wheel 130 corresponds to the spacing of the carriers 27 so that a carrier 27 is always in register with a carrier 25 when the chains 13, 23 are synchronized. In a modification, Fig: 6, the arm 310 corresponding to arm 110 is adjustable' relative to the gear 104 to obtain exact registration of the carriers 25, 27 by a sector-plate carried by the arm 310 meshing with a pinion carried by the gear 104 and manually adjustable. The sector is then locked to the gear 104 by a bolt 319 passed through a slot 311 in gear 104 and engaging the sector plate.