Bobbin thread replenishing mechanism for sewing machines

Claim 2

In a lockstitch sewing machine having a cup-shaped circularly moving loop taker including a peripheral rim formed with a thread seizing beak, a thread carrying bobbin journalled in said loop taker, and a thread carrying needle supported for endwise reciprocating movement in a path which traverses the plane in which the thread seizing beak moves and extends between the loop taker rim and the bobbin, means for replenishing thread on said bobbin while in said loop taker from thread carried by said needle including means for directing thread from said needle onto said bobbin, bobbin rotating mechanism for winding thread from the needle onto the bobbin during circular movement of said loop taker and reciprocatory movement of said needle, and thread guiding means effective to constrain the thread leading to the bobbin during bobbin thread replenishment in a path which extends inside the cup-shaped loop taker and within the plane in which the thread seizing beak moves so as to prevent the formation of needle thread loops in the path of the loop taker thread seizing beak while the bobbin thread is being replenished.

Claim 3

A circularly moving sewing machine loop taker having a cup-shaped body formed at the rim with an inwardly extending loop seizing beak adapted to cooperate in the formation of lockstitches with a thread carrying needle which is endwise reciprocatory in a path substantially parallel to the axis of movement of said loop taker, a stationary bobbin case journalled in said loop taker and accommodating a thread carrying bobbin therein, means for replenishing thread on said bobbin while in place in said loop taker from thread carried by said needle comprising a spring element on said bobbin case for applying tension to a thread leading to said bobbin, means on said bobbin case formed with a thread guiding slot for directing a loop of needle thread seized by said loop taker beak to the influence of said spring element, said thread guiding slot being open at one extremity toward which said loop taker beak moves carrying a seized needle thread loop, and being closed at the opposite extremity, said closed thread guiding slot extremity being positioned so that the shortest path for that limb of the needle thread loop extending therefrom to the path of needle reciprocation occurs within said cup-shaped loop taker body between the bobbin case and the loop taker, means for directing into the bobbin the other limb of a needle thread loop introduced into said thread guiding slot and a device for rotating said bobbin to wind thread thereon.

Claim 4

A circularly moving sewing machine loop taker having a cup-shaped body formed at the rim with an inwardly extending loop seizing beak adapted to cooperate in the formation of lockstitches with a thread carrying needle which is endwise reciprocatory in a path substantially parallel to the axis of movement of said loop taker, a stationary bobbin case journalled in said loop taker and accommodating a thread carrying bobbin therein, means for replenishing thread on said bobbin while in place in said loop taker from thread carried by said needle comprising a spring element on said bobbin case for applying tension to a thread leading to said bobbin, means on said bobbin case formed with a thread guiding slot for directing a loop of needle thread seized by said loop taker beak to the influence of said spring element, said thread guiding slot being open at one extremity toward which said loop taker beak moves carrying a seized needle thread loop, and being closed at the opposite extremity, said closed thread guiding slot extremity being positioned so that the shortest path for that limb of the needle thread loop extending therefrom to the path of needle reciprocation occurs within said cup-shaped loop taker body between the bobbin case and the loop taker, means for directing into the bobbin the other limb of a needle thread loop introduced into said thread guiding slot and a device for rotating said bobbin to wind thread thereon.

Claim 5

A circularly moving sewing machine loop taker as set forth in claim 2 in which said means for directing said limb of needle thread loop to the bobbin comprises means supporting one flange of said bobbin exteriorly of said bobbin case, and said exteriorly supported bobbin flange being formed with a radial slot for accommodating passage into the bobbin of said other limb of needle thread loop.

Claim 6

A circularly moving sewing machine loop taker as set forth in claim 3 in which said means on said bobbin case formed with a thread guiding slot extends adjacent to a protective shoulder formed on said bobbin case for preventing needle thread loops being manipulated by said loop seizing beak from entering said thread guiding slot, and a thread camming finger shiftably supported on said sewing machine adjacent to said loop taker and having an effective position contiguous to said protective shoulder for urging a needle thread loop being manipulated by said loop taker beak into said thread guiding slot.

Claim 7

A circularly moving sewing machine loop taker as set forth in claim 4 in which said thread camming finger is carried by an operator influenced element shiftably supported adjacent to the loop taker, and in which a thread cutting blade is carried by said operator influenced element for movement into a position overlying the radial slot in said bobbin flange when said thread camming finger occupies an effective position.