Weft thread tensioning device and method of operating a weft thread tensioning device

Abstract

A weft thread tensioning device includes a weft thread path defining arrangement having two weft thread passage elements positioned at a distance with respect to each other for receiving a weft thread such as to extend along a straight weft thread path extending between the weft thread passage elements. A weft thread deflection element is positioned between the weft thread passage elements in the direction of the weft thread path. The weft thread deflection element is movable to act on a weft thread extending across the weft thread passage elements deflecting the weft thread between the weft thread passage elements out of the straight weft thread path. A deflection element drive moves the weft thread deflection element and includes a controller associated therewith for controlling the movement of the weft thread deflection element for deflecting a weft thread extending across the weft thread passage elements.

1 . A weft thread tensioning device, comprising:
 - a weft thread path defining arrangement having two weft thread passage elements positioned at a distance with respect to each other for receiving a weft thread such as to extend along a straight weft thread path extending between the weft thread passage elements,   a weft thread deflection element positioned between the weft thread passage elements in the direction of the weft thread path, the weft thread deflection element being movable such as to act on a weft thread extending across the weft thread passage elements for deflecting the weft thread between the weft thread passage elements out of the straight weft thread path, and   a deflection element drive operable for moving the weft thread deflection element, the deflection element drive having a controller associated therewith for controlling the movement of the weft thread deflection element for deflecting a weft thread extending across the weft thread passage elements,   wherein the deflection element drive comprises a rotary electric motor, and that the weft thread deflection element is coupled to a rotor shaft of the rotary electric motor and is arranged for carrying out a swiveling movement about a swivel axis that is substantially parallel to the straight weft thread path.   
     
     
         2 . The weft thread tensioning device according to  claim 1 , wherein the weft thread deflection element is positioned in a center area between the weft thread passage elements in the direction of the straight weft thread path. 
     
     
         3 . The weft thread tensioning device according to  claim 1 , wherein the weft thread deflection element comprises a deflection lever connected to a deflection shaft rotatable about the swivel axis, the deflection lever extending from the swivel axis with a lever length exceeding a distance between the weft thread passage elements and the swivel axis. 
     
     
         4 . The weft thread tensioning device according to  claim 1 , wherein at least one of the weft thread passage elements has a weft thread passage opening for receiving a weft thread such as to extend through the weft thread passage opening. 
     
     
         5 . A method of operating a weft thread tensioning device comprising:
 a weft thread path defining arrangement having two weft thread passage elements positioned at a distance with respect to each other for receiving a weft thread such as to extend along a straight weft thread path extending between the weft thread passage elements,   a weft thread deflection element positioned between the weft thread passage elements in the direction of the weft thread path, the weft thread deflection element being movable such as to act on a weft thread extending across the weft thread passage elements for deflecting the weft thread between the weft thread passage elements out of the straight weft thread path, and   a deflection element drive operable for moving the weft thread deflection element, the deflection element drive having a controller associated therewith for controlling the movement of the weft thread deflection element for deflecting a weft thread extending across the weft thread passage elements, the method comprising:   in a first deflection operating mode, the deflection element drive is controlled such as to move the weft thread deflection element to a predetermined deflection position upon each deflection operation, and   in a second deflection operating mode, the deflection element drive is controlled such as to apply a controlled deflection drive force to the weft thread deflection element.   
     
     
         6 . The method according to  claim 5 , wherein, in the first deflection operating mode, the deflection element drive is controlled such as to move the weft thread deflection element from a starting position or an intermediate position to the predetermined deflection position upon each deflection operation, wherein, when being positioned in the starting position, the weft thread deflection element does not interact with a weft thread extending across the weft thread passage elements for deflecting a weft thread out of the straight weft path and, when being positioned in the intermediate position, the weft thread deflection element is positioned between the starting position and the predetermined deflection position, and wherein, when being moved from the starting position towards the deflection position, the weft thread deflection element is moved across the straight weft thread path for deflecting a weft thread extending across the weft thread passage elements, a maximum weft thread deflection being obtained when the weft thread deflection element is positioned in the predetermined deflection position. 
     
     
         7 . The method according to  claim 6 , wherein at least one deflection operation is carried out during a weft insertion cycle. 
     
     
         8 . The method according to  claim 7 , wherein a plurality of deflection operations are carried out during a weft insertion cycle. 
     
     
         9 . The method according to  claim 5 , wherein, in the first deflection operating mode, the predetermined deflection position is kept constant for at least two consecutive deflection operations and/or at least two consecutive weft insertion cycles. 
     
     
         10 . The method according to  claim 5 , wherein, in the first deflection operating mode, the predetermined deflection position is varied between at least two consecutive deflection operations and/or at least two consecutive weft insertion cycles. 
     
     
         11 . The method according to  claim 5 , wherein, in the second operating mode, the deflection element drive is controlled such as to move the weft thread deflection element from a starting position towards a deflection position, wherein, when being positioned in the starting position, the weft thread deflection element does not interact with a weft thread extending across the weft thread passage elements for deflecting a weft thread out of the straight weft path, and wherein, when being moved from the starting position towards the deflection position, the weft thread deflection element is moved across the straight weft thread path for deflecting a weft thread extending across the weft thread passage elements, wherein the predetermined deflection drive force applied to the weft thread deflection element is varied in dependence on a counter force applied by the deflected weft thread to the weft thread deflection element. 
     
     
         12 . The method according to  claim 11 , wherein the predetermined deflection drive force is adjusted such as to provide a spring-like force characteristic, such that an increasing counter force applied to the weft thread deflection element leads to an increasing deflection drive force. 
     
     
         13 . The method according to  claim 5 , wherein the second deflection operating mode is maintained during at least one weft insertion cycle. 
     
     
         14 . The method according to  claim 5 , wherein the second deflection operating mode is maintained during a plurality of consecutive weft insertion cycles. 
     
     
         15 . The method according to  claim 5 , wherein the first deflection operating mode is used, if the number of weft insertion cycles per minute is above 20, and wherein the second deflection operating mode is used, if the number of weft insertion cycles per minute is below or at 20. 
     
     
         16 . The method according to  claim 5 , wherein the first deflection operating mode is used in association with a weft thread, if this weft thread is selected for the insertion into a shed formed between warp threads during a weft insertion cycle, and wherein the second deflection operating mode is used in association with a weft thread, if this weft that is not selected for the insertion into a shed formed between warp threads during a weft insertion cycle.