Sewing machine

Abstract

A lower end of a thread guide lever, which is rockably attached to a lower looper and supports a thread pipe, and an air ejecting unit, which faces a thread inserting hole of the thread pipe and ejects air toward the thread inserting hole, are coupled via a coupling member so that they are interlocked with each other. The coupling member is moved such that a discharging port of an air nozzle is positioned at an ejecting position close to the thread inserting hole when a thread discharging hole is positioned at a threading position which is coincident with a thread hole of a lower looper, and such that the air nozzle is moved to a standby position when the thread discharging hole is moved to a retreating position.

Description

[0001]The present invention claims priority from Japanese Patent Application No. 2006-218233 filed on Aug. 10, 2006, the entire content of which is incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to a sewing machine having a threading device for inserting a thread through a looper.BACKGROUND ART[0003]Some sewing machines, such as an over-edge overlock sewing machine and a double chainstitch sewing machine, has a threading device for inserting a thread through a looper by utilizing pressurized air (see, e.g., JP 2005-318932 A). As shown in FIGS. 11 to 13, such a threading device includes a lower looper driving mechanism 500 having a lower looper 510. The lower looper 510 has an extended portion 510a which is inserted into a loop of a needle thread by moving the extended portion 510a back and forth in synchronization with a vertical motion of a needle. The threading device further includes a thread pipe 520, a thread guide lever 530 which moves the ...

AI Technical Summary

Benefits of technology

[0047]According to one or more aspects of the invention, when the thread path member (the thread pipe) is moved to the threading position by the interlocking means (the interlocking mechanism), the air ejecting means (the air ejecting unit) is moved to the ejecting position. Similarly, when the air ejecting means (the air ejecting unit) is moved to the ejecting position, the thread path member (the thread pipe) is moved to the threading position. Namely, when one of the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) is operated, the other is also operated at the same time. Consequently, the operation for inserting the thread through the looper is simplified than the background art. In addition, a certain operating procedure is not required. Therefore, the threading operation can easily be carried out. As a result, it is possible to enhance an operability of the sewing machine.

[0048]According to one or more aspects of the invention, the thread path member moving means (the thread pipe moving mechanism) is driven by the first actuator and the air ejection moving means (the air ejection moving mechanism) is driven by the second actuator. Moreover, the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) are driven by the interlocking control means (the interlocking control portion) such that mutual operating directions are coincident with each other. Namely, the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) are electrically interlocked with each other. Accordingly, it is possible to automatically position the thread discharging hole of the thread path member (the thread pipe) at the threading position. Thus, it is possible to easily insert the lower looper thread into the looper. Furthermore, it is also possible to automatically position the thread discharging hole of the thread path member (the thread pipe) at the retreating position. Moreover, it is possible to interlock the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) without directly connecting them mechanically. Therefore, it is possible to enhance a degree of freedom of the arrangement in the sewing machine.

[0049]According to one or more aspects of the invention, the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) are mechanically connected, and are interlocked by the coupling member. Therefore, the cost can be reduced due to a simple structure.

[0051]Namely, it is possible to electrically control the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) while reducing a cost by using one actuator and the coupling member. In addition, the detecting means (the detecting sensor) may be provided to detect that the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) are positioned at predetermined positions. In such as case, it is possible to control the thread path member moving means (the thread pipe moving mechanism) and the air ejection moving means (the air ejection moving mechanism) to be automatically stopped at the predetermined positions.

[0052]According to one or more aspects of the invention, the ejection control means (the ejection control portion) stops the spindle at the predetermined rotating angle based on the detection of the spindle angle detecting means (the spindle angle detecting sensor) and drives the actuator to position the air ejecting means (the air ejecting unit) at the ejecting position when the instruction to start the threading operation for inserting the lower looper thread through the looper is input from the input means (input portion), whereby the thread discharging hole of the thread path member (the thread pipe) is positioned at the threading position. Accordingly, it is possible to easily carry out the threading work for inserting the thread through the looper. Thus, it is possible to enhance an operability of the sewing machine.

[0054]According to one or more aspects of the invention, the thread discharging hole of the thread path member (the thread pipe) is positioned at the retreating position in accordance with the driving operation of the sewing machine motor by the returning means (the guide member). Moreover, the air ejecting means (the air ejecting unit) is positioned at the standby position via the interlocking means (the interlocking mechanism). Consequently, it is possible to smoothly make a transition to the sewing operation even in a case where a user forgets to return the thread discharging hole of the thread path member (the thread pipe) to the retreating position after inserting the lower looper thread through the thread hole of the looper. In other words, the user of the sewing machine does not need to return the thread discharging hole of the thread path member (the thread pipe) from the threading position to the retreating position after inserting the thread through the looper. Consequently, it is possible to easily carry out the work for inserting the thread through the looper. As a result, it is possible to enhance the operability of the sewing machine.

Problems solved by technology

Thus, there is a problem that such a operation for changing the lower looper thread T is complicated because many portions needs to be operated.

Furthermore, there is a problem that a great deal of time and labor is required for the operation because the operation needs to be carried out in accordance with a certain procedure.

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