| 摘要 |
Air is conveyed pneumatically to and through a tobacco feed chute by continuously extracting air from a region in the feed chute and continuously applying air upstream of that region in the direction of movement of the tobacco. The feed chute may include a seal or valve comprising at least one roller defining a throat in the feed chute, the or each roller being rotatable such that in the throat the or each roller surface moves in the same direction as the tobacco, a plurality of vanes mounted on and displaceable radially with respect to the or each roller, a cam arrangement for controlling the radial displacement of the vanes such that they change from being extended in a region away from the throat to being fully retracted in the throat so as to draw air from downstream of the seal, between the vanes, to upstream of the seal, and a flow restricting arrangement for the or each roller for accelerating the drawn air into the throat from an upstream position.
|
