Yarn feeding device for a textile machine, especially a knitting machine

A yarn feeding device for a yarn-consuming textile machine, said yarn feeding device comprising:

• means for positively feeding yarn (79) to a textile machine to form a finished product according to a predetermined variable yarn consuming speed of the textile machine as determined by predetermined yarn consumption information including yarn consuming speed changes and timings of said yarn consuming speed changes, said means for positively feeding yarn (79) including a rotary yarn feeding element (1,83) for carrying a main yarn reserve (84), motor means (82) for rotating said rotary yarn feeding element (1,83) at a motor rotation speed according to said yarn consuming speed as determined by said predetermined yarn consumption information and means (51, 57) for controlling said motor means including microprocessor means for storing said predetermined yarn consumption information and for controlling the motor rotation speed according to said predetermined yarn consumption information, wherein said yarn feeding element (1,83) and said motor means (82) have an inertia limiting a rate at which said motor rotation speed can be changed;
• yarn reserve means (3,78;
• 20, 77) for building up or reducing an auxiliary yarn reserve comprising a portion of said yarn extending between said main yarn reserve and said textile machine, when changes in said yarn consuming speed occur that are so rapid that said motor means (82) temporarily cannot change said motor rotation speed to deliver said yarn from said rotary yarn feeding element at said yarn consuming speed because of said inertia;
• and
• means for controlling said yarn reserve means (3,78;
• 20,77) to increase or decrease said portion of said yarn in said auxiliary yarn reserve so that, whenever said predetermined yarn consuming speed of said textile machine changes, said yarn is fed to said textile machine at said yarn consuming speed of said textile machine in accordance with said predetermined yarn consumption information in spite of said inertia of said motor means and said yarn feeding element.