Source: {"pile_set_name": "USPTO Backgrounds"}

The present invention relates to a fiber opening device in a spinning unit of an open-end spinning machine, and more particularly such a device having an opening roller rotatably mounted in a housing to which a sliver is fed by a drawing-in roller.
In open-end spinning, a sliver consisting of fibers that are generally parallel is combed to separate the fibers by an opening roller enclosed in a housing and the fibers are fed by air current in the housing to a fiber discharge opening in the housing from which they pass through a fiber guide tube to the spinning element, e.g. a spinning rotor.
As the fibers are of small size, even very small crevices between and within the components of the device, such as at edges and corners, can result in entrapment of individual fibers and the accumulation of a clump of fibers that disrupts the even flow of fibers that may ultimately break loose and pass into the spinning rotor to create a faulty slub in the yarn.
Typical of the known fiber opening devices in open-end spinning machines is the device disclosed in German patent document DE-PS No. 19 14 115, in which a trash discharge opening for separating trash, such as hull particles, dirt, etc., is formed in the housing between the drawing-in roller and the fiber discharge opening to the guide tube. Such a trash discharge opening will allow undesirable clumps of fibers to be discharged and not pass through the guide tube to the rotor, but it does not prevent the formation of clumps, which can result in faulty yarn, e.g. thin areas, during the formation of a clump of fibers prior to being broken loose and discharged. In known fiber opening devices, there are several locations at which fibers can be caught and accumulate in crevices. Typical of these are the pivoted feed trough, the drawing-in trough and the corners between the housing sidewalls and circumferential wall.