Cop winder with controlled yarn tension

Claim 1

In a yarn winder of the type including rotatable yarn-winding means, a variable speed motor driving the yarn winding means to wind thereon yarn fed thereto at a substantially constant given feeding speed, yarn feeler means including pivotally supported arm means and a spring-biased dancer pulley carried rotatably by the arm means and engaged in a loop of the yarn in advance of the yarn-winding means, motor speed-adjusting means operable, responsive to swinging of the dancer pulley about the pivot axis of the arm means, to adjust the motor speed to compensate for differences between the yarn-feeding speed and the yarn-winding speed, the adjusting means including a motor supply circuit comprising an electric signal controlled adjustable supply and a control circuit, sensitive to the actual position of said arm means, providing a control signal for adjusting the supply as a function of such swinging of the dancer pulley; the improvement comprising, in combination, movable contact means; means frictionally coupling said movable contact means to said arm means for frictional displacement by said arm means concurrently with said swinging of said dancer pulley; limiting means cooperable with said movable contact means and limiting the motion of said movable contact means within an amplitude less than that of said swinging of said dancer pulley; fixed contact means positioned for engagement by said movable contact means when said movable contact means is moved in one direction of the swinging of said dancer pulley and concurrently with said swinging; auxiliary adjusting circuit means connected to said control circuit and including said movable and fixed contact means; said auxiliary adjusting circuit being activated upon engagement between said movable and fixed contact means to modulate said control circuit to apply, to said adjustable supply, a control signal providing a sharp variation of the motor supply.