Needle bar thread guide for sewing machine

Abstract

A needle bar thread guide for a sewing machine includes a thread guide part located in a thread hooking part of a thread hooking member to guide the needle thread into the thread hooking part, and a thread cast-off preventing member having a thread cast-off preventing part closing the thread guide part. The thread cast-off preventing member is elastically deformable. The thread cast-off preventing part has a distal end which is in contact with an upper surface of the thread hooking part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present disclosure will become clear upon reviewing the following description with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a lock stitch sewing machine in accordance with a first example of the present invention;

FIG. 2 is a front view of a needle bar connecting stud and a needle bar thread guide of the lock stitch sewing machine;

FIG. 3 is a bottom view of the needle bar connecting stud and the needle bar thread guide of the lock stitch sewing machine;

FIG. 4 is a right side view of the needle bar connecting stud and the needle bar thread guide of the lock stitch sewing machine;

FIG. 5 is a perspective of a thread cast-off preventing member of the lock stitch sewing machine;

FIG. 6 is a front view of the thread cast-off preventing member;

FIG. 7 is a plan view of the thread cast-off preventing member;

FIG. 8 is a right side view of the thread cast-off preventing member;

FIG. 9A is a view similar to FIG. 3, showing the condition in the case where the thread hooking starts;

FIG. 9B is a view similar to FIG. 3, showing the condition in the case where the thread hooking is under execution;

FIG. 9C is a view similar to FIG. 3, showing the condition in the case where the thread hooking has been completed;

FIG. 9D is a view similar to FIG. 3, showing the condition in the case where a horizontal plate part turns largely during the thread hooking;

FIG. 10A is a view similar to FIG. 3, showing the condition in the case where the thread disengagement starts;

FIG. 10B is a view similar to FIG. 3, showing the condition in the case where the thread disengagement is under execution;

FIG. 10C is a view similar to FIG. 3, showing the condition in the case where the thread disengagement has been completed;

FIG. 10D is a view similar to FIG. 3, showing the condition in the case where a horizontal plate part turns largely during the thread disengagement;

FIG. 11 is a view similar to FIG. 7, showing a second example of the present invention; and

FIG. 12 is a view similar to FIG. 7, showing a third example of the present invention.

Claims

1. A needle bar thread guide for a sewing machine which includes a needle bar supporting a sewing needle with a lower end and a thread hooking member provided on the lower end of the needle bar to hook a needle thread, the thread hooking member including a thread hooking part with an upper surface, the needle bar thread guide comprising: a thread guide part provided in the thread hooking part of the thread hooking member to guide the needle thread into the thread hooking part; anda thread cast-off preventing member having a thread cast-off preventing part closing the thread guide part, the thread cast-off preventing member being elastically deformable, the thread cast-off preventing part having a distal end which is in contact with the upper surface of the thread hooking part.

2. The needle bar thread guide according to claim 1, wherein when the needle thread is moved through the thread guide part to the thread hooking part, the thread cast-off preventing member is elastically deformed so that the needle thread is moved into the thread guide part thereby to be hooked by the thread hooking part.

3. The needle bar thread guide according to claim 1, wherein the distal end of the thread cast-off preventing part is formed so as to be curved downward and is in point-contact with the upper surface of the thread hooking part.

4. The needle bar thread guide according to claim 1, wherein the thread cast-off preventing member comprises a leaf spring and has a horizontal plate part continuous to the distal end of the thread cast-off preventing part, an elastically deformable rising part extending upward from the horizontal plate part and having an upper end, and a fixed plate part continuous to the upper end of the rising part.

5. The needle bar thread guide according to claim 4, wherein the horizontal plate part of the thread cast-off preventing member includes a stopper part limiting a moving range of the horizontal plate part so that the distal end of the thread cast-off preventing part is prevented from disengaging from the thread hooking part when the distal end of the thread cast-off preventing part is moved horizontally.

6. The needle bar thread guide according to claim 5, wherein the horizontal plate part has an elongate hole which is formed through the horizontal plate part so that the needle is passed through the hole, and the stopper part is comprised of an edge of the elongate hole.