Shredded tobacco supply device for a cigarette manufacturing machine

A shredded tobacco supply device for a cigarette manufacturing machine, comprising:

• a gravity chute through which shredded tobacco supplied thereto is let fall down, said gravity chute having a lower end for discharging the falling shredded tobacco therefrom;
• a separation throat diverging sideways from an intermediate portion of said gravity chute and having an inlet opening into said gravity chute and an outlet spaced apart from the inlet in the diverging direction;
• a primary separator for separating the shredded tobacco falling down through said gravity chute into light shreds which are introduced into said separation throat, and heavy shreds which are allowed to fall down through said gravity chute, in accordance with weights of the shreds, said primary separator producing a primary air jet traversing an interior of said gravity chute and directed toward the inlet of said separation throat;
• a fluid bed trough extending from the outlet of said separation throat to a tobacco band of the cigarette manufacturing machine, said fluid bed trough having a conveyance surface for guiding the light shreds delivered from the outlet of said separation throat toward the tobacco band;
• a separation duct extending downward from the conveyance surface, said separation duct having an open end opening in the conveyance surface in the vicinity of the outlet of said separation throat and directed toward the tobacco band, and a reception opening formed at an intermediate position thereof, the reception opening being connected to the lower end of said gravity chute for receiving the heavy shreds from said gravity chute into said separation duct;
• a secondary separator for separating the heavy shreds received by said separation duct into recovery shreds which are lifted upward through said separation duct and delivered onto the conveyance surface of said fluid bed trough, and reject shreds which are allowed to fall down through said separation duct, in accordance with weights of the heavy shreds, said secondary separator emitting a secondary air jet from a position of said separation duct upward of the reception opening, the secondary air jet being directed toward the open end and creating a rising current within said separation duct for lifting the recovery shreds upward;
• and
• an air confluent nozzle extending from the outlet of said separation throat, said air confluent nozzle having a cross-sectional flow area gradually decreasing with distance from the outlet of said separation throat toward the tobacco band and producing a transport flow by joining together the primary air jet from the outlet of said separation throat and the secondary air jet from the open end of said separation duct, the transport flow causing a shred mixture of the light shreds delivered from the outlet of said separation throat and the recovery shreds delivered from the open end of said separation duct to be conveyed along the conveyance surface of said fluid bed trough toward the tobacco band.