Bobbin thread feeder of sewing machine

Abstract

The present invention provides a bobbin thread feeder of sewing machine of simple structure in which a lower thread can be reliably fed at an appropriate tension. A lower thread bobbin 21 can be removably contained through an opening for containing a lower thread bobbin 17 in a rotary hook 20 of a horizontal rotary hook 30 provided in a sewing machine frame. A thread tension plate and a thread tension spring are attached while overlapping along the inner circumference of the rotary hook 20, and function as a tension generating portion 22 for imparting resistance to pulling out a lower thread being guided through the gap between the thread tension plate and the thread tension spring. A needle plate 16 with an opening for taking the lower thread bobbin 21 in and out is provided above the rotary hook 20. The needle plate 16 comprises a guiding slit 27 that guides the lower thread formed thereon. The guiding slit 27 is formed substantially linearly in the extending direction of the overlapping portion of the thread tension plate and the thread tension spring.

1 . A bobbin thread feeder of sewing machine, in which
 a lower thread bobbin can be removably contained through an opening for containing the lower thread bobbin in a rotary hook of a horizontal rotary hook provided in a sewing machine frame, and in which   a tension generating portion is provided for imparting a resistance to a lower thread being pulled out while passing and being guided between a thread tension plate and a thread tension spring, which are attached while overlapping along the inner circumference of the rotary hook, wherein   a needle plate with an opening for taking the lower thread bobbin in and out is provided above the rotary hook,   the needle plate has a thread-cutting portion for cutting the lower thread, and a guiding slit for guiding the lower thread to a position near the thread-cutting portion, and   the guiding slit is formed toward the side away from a user substantially linear in a direction for circumscribing the inner circumference of the rotary hook at a portion where the lower thread is pulled out of the tension-generating portion.   
   
   
       2 . The bobbin thread feeder of sewing machine according to  claim 1 , wherein a lower side of an edge on the side of a needle hole of the guiding slit on the needle plate is chamfered.