Needle bar driver assembly for a sewing machine

Abstract

There is provided a needle bar driver assembly for an overlock sewing machine. The overlock sewing machine has a needle for penetrating a material to be sewed, a needle bar for securing the needle thereto, and a throat plate for allowing the needle to pass there through. The needle bar driver assembly includes a needle bar connecting link assembly for driving the needle bar. The needle bar driver assembly further includes an oscillating needle bar driving assembly for driving the needle bar connecting link assembly and for raising said needle bar connecting link assembly such that the needle is more than 18 mm above the throat plate.

What is claimed is:  
     
         1 . A needle bar driver assembly for an overlock sewing machine having a needle for penetrating a material to be sewed, a needle bar for securing the needle thereto, and a throat plate for allowing the needle to pass there through, the needle bar driver assembly comprising: 
 a needle bar connecting link assembly for driving the needle bar; and    an oscillating needle bar driving assembly for driving the needle bar connecting link assembly and for raising said needle bar connecting link assembly such that the needle is more than 18 mm above the throat plate.    
     
     
         2 . The needle bar driver assembly of  claim 1 , wherein the overlock sewing machine further has a looper for manipulating a thread, and said oscillating needle bar driving assembly drives the needle bar connecting link assembly such that the needle is synchronized with a timing of the looper.  
     
     
         3 . A method for controlling a needle of an overlock sewing machine, the needle for penetrating a material to be sewed, the overlock sewing machine further including a needle bar for securing the needle thereto, and a throat plate for allowing the needle to pass there through, the method comprising the steps of: 
 driving the needle bar; and    raising the needle bar such that the needle is more than 18 mm above the throat plate.    
     
     
         4 . The method of  claim 3 , wherein the overlock sewing machine further comprises a looper for manipulating a thread, and said driving step comprises the step of driving the needle bar in synchronization with a timing of the looper such that the needle is synchronized with the timing of the looper.  
     
     
         5 . A needle bar driver assembly for an overlock sewing machine, comprising: 
 a needle bar connecting link assembly, for driving a needle bar; and    an oscillating multi-part needle bar driving assembly, capable of being in a closed condition and an open condition, for transferring oscillatory motion to said needle bar connecting link assembly in the closed condition and for lifting the needle bar connecting link assembly to extend an upper travel limit of said needle bar connecting link assembly in the open condition.    
     
     
         6 . The needle bar driver assembly of  claim 5 , wherein said oscillating multi-part driver bar assembly comprises an upper link, an outer link, a coupling link, and a main beam, the upper link and the outer link both rotatably coupled to the main beam, the outer link further rotatably coupled to said needle bar connecting link assembly, the upper link and the outer link further operatively coupled together via the coupling link such that a position of the outer link tracks the position of the upper link, said oscillating multi-part driver bar assembly capable of being in the closed condition corresponding to a closed position of the upper link with respect to the main beam and capable of being in an open condition corresponding to an open position of the upper link with respect to the main beam.  
     
     
         7 . The needle bar driver assembly of  claim 6 , wherein the upper link and the outer link are operatively together by the coupling link using a tongue and groove structure.  
     
     
         8 . The needle bar driver assembly of  claim 7 , wherein the tongue and groove structure is disposed between the coupling link and the outer link.  
     
     
         9 . The needle bar driver assembly of  claim 5 , further comprising: 
 an opposing spring, connected to the oscillating multi-part driver bar assembly, for applying downward pressure to the oscillating multi-part driver bar assembly to at least one of limit an upper travel limit of the oscillating multi-part driver bar assembly, encourage the oscillating multi-part driver bar assembly to rotate back into the closed condition, and prevent the oscillating multi-part driver bar assembly from locking in the open condition.    
     
     
         10 . The needle bar driver assembly of  claim 5 , further comprising an actuator for alternately placing the oscillating multi-part driver bar assembly into the open condition and the closed condition.