JP3404416B2 - Operation switching device for sewing machine thread tensioner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation switching device for a thread tensioner of a sewing machine. 2. Description of the Related Art Conventionally, in an operation switching device for a thread tensioner of a sewing machine, the operation of the thread tensioner is switched between the operation state and the non-operation state in conjunction with the vertical operation of a presser foot lifting lever. I have. Therefore, when the upper thread is hooked, the thread is inserted between the thread tension discs with the presser foot lifting lever raised and the thread tension device inactive. However, if the operator neglects the above operation and lowers the presser foot lifting lever, that is, if the upper thread is hooked while the thread tensioner is in operation, the upper thread becomes thread tensioner. If the sewing is performed as it is without being securely inserted between the plates, the needle thread tension is weak, and there is a problem that satisfactory sewing cannot be obtained. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. When the presser lifting lever is once raised by taking out or putting in a cloth, the lifting operation is performed even when the presser lifting lever is kept lowered. When the thread is hooked, the thread is securely inserted into both the tone plates. In order to achieve this object, an apparatus for switching the operation of a thread tensioner of a sewing machine according to the present invention comprises the steps of first raising a presser foot lifting lever and then lowering the presser foot lifting lever.
A holding member for holding the inoperative state of the thread tensioner even when the thread tensioner is turned on, and a release means for changing the thread tensioner from the inactive state to the active state while the upper shaft of the sewing machine makes one rotation. I have. The holding member of the operation switching device for the thread tensioner of the present invention having the above-mentioned structure is such that when the presser foot lifting lever is once raised, the thread tensioner is inactive even if the presser foot lifting lever is then lowered. Hold. Then, the releasing means changes the thread tensioner from the inactive state to the active state while the upper shaft of the sewing machine makes one rotation. An embodiment of the present invention will be described below with reference to the drawings. First, the presser lifting lever 1 rotates about a shaft 2 fixed to a sewing machine body (not shown). The thread tensioner (set) 3 is fixed to the sewing machine main body, and its main components are two thread tension discs 3a, a thread tension spring 3b, and a first thread release plate 3
c, which is the same as a known configuration. Between the first thread loosening plate 3c and the presser lifting lever 1, a second thread loosening plate 5 rotatable about a shaft 4 fixed to the sewing machine main body.
Is provided. The presser bar 7 slides up and down in the guide hole of the sewing machine main body. The holding bar holder 8 is fixed to the holding bar 7. The bush 10 is fixed to the upper shaft 9, and an elastic arm (release means) 11 is attached to the bush 10. One end 1 of arm member (holding member) 12
2a is mounted so as to be rotatable around a shaft 13 fixed to the second thread loosening plate 5 and to be able to swing slightly in the direction of the upper shaft 9. The other end 12b of the arm member 12 is supported by a guide member 14 fixed to the sewing machine main body. A force is applied to the other end 12b in the right direction and the upper shaft 9 direction by a spring 15 attached to the sewing machine main body. Further, the other end 12b is provided with a notch 12c and a protrusion 12d. Next, the operation of the sewing machine of this embodiment will be described with reference to FIGS. In the state shown in FIGS. 1 to 3 (the presser lifting lever 1 is lowered), one end 5 a of the second thread release plate 5 is in contact with the cam surface 1 a of the presser lifting lever 1. At this time, the two thread tension discs 3a are compressed by the thread tension spring 3b, and the thread tension device 3 is in an operating state. The presser bar 7 is down. When the holding lever 1 is rotated from this state to the state shown in FIGS. 4 and 5, the holding rod holder 8 is pushed up by the cam surface 1b of the holding lever 1, and the holding rod 7 is raised. One end 5a of the second thread loosening plate 5 is pushed by the cam surface 1c of the press-up lever 1, and the second thread loosening plate 5 rotates around the shaft 6. As a result, the other end 5b of the second thread-releasing plate 5 presses the first thread-releasing plate 3c, and a gap is formed between the two thread tension discs 3a, thereby creating an inoperative state of the thread tension device. At this time, the arm member 12 moves to the left by the rotation of the second thread loosening plate 5. With the movement, when the notch 12c passes through the guide part 14, the step difference of the notch 12c and the other end 12b of the arm member 12 move in the direction of the upper shaft 9 by the force of the spring 15. When the press-up lever 1 is lowered again, the state shown in FIGS. 5 and 6 is reached, and the press bar 7 is lowered. The second thread loosening plate 5 attempts to return to the state shown in FIGS. 1 to 3 by the force of the spring 15, but the notch 1
2c is interfered by the guide portion 14, and the state of FIGS. 4 and 5 is maintained. Therefore, the thread tensioner 3 maintains the inoperative state. In this state, the sewing machine is operated, and when the upper shaft 9 starts to rotate, the protrusions 12 on the rotation track of the arm piece 11 are rotated.
When the sewing machine stops, the arm piece 11 in the phase as shown in FIG. 3 immediately interferes (see FIG. 7), and as a result, the notch 12c comes off the guide part 14 and becomes the state shown in FIGS. The tone adjuster 3 is in an operating state. Also, the protrusion 12 of the arm member 12
d moves away from the rotation trajectory of the arm 11 and does not interfere with each other even if the sewing machine is operated unless the lifting lever 1 is raised again. As is apparent from the above description, according to the present invention, when the lifting lever is once raised,
Until the upper shaft starts to rotate, the thread tensioner does not operate.Therefore, once the lifting lever is raised by taking out or putting in the cloth, the thread can be securely removed even when the lifting lever is lowered. Hanging can be done.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing a configuration of a switching device according to the present embodiment. FIG. 2 is a top view of the switching device. FIG. 3 is a side view of the switching device. FIG. 4 is a front view of the switching device with the presser lifting lever raised. FIG. 5 is a top view of the switching device with the presser lifting lever raised. FIG. 6 is a front view of a state in which the presser lifting lever of the switching device is once raised and then lowered again. FIG. 7 is a view showing a state where the arm piece pushes the arm member when the upper shaft starts rotating in FIG. 6; [Description of Signs] 1 Presser lifting lever 3 Thread tensioner 9 Upper shaft 10 Bush 11 Arm piece (holding member) 12 Arm member (release means) 14 Guide member

Claims (1)

(57) [Claims] [Claim 1] In a sewing machine in which a thread tension device is switched to an inactive state by raising a presser foot lifting lever, the presser foot lifting lever is once raised and then the presser foot lifter is lifted.
A holding member for holding the inoperative state of the thread tensioner even when the tensioning lever is lowered, and a state in which the thread tensioner is operated from the inoperative state by acting on the holding member while the upper shaft of the sewing machine makes one rotation. An operation switching device for a thread tensioner, comprising: a release unit for performing the operation described above.