JP2008295474A - Bobbin thread feeder of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bobbin thread feeder of sewing machines which is capable of surely feeding a bobbin thread at an appropriate tension and has a simple structure. <P>SOLUTION: An inner rotary hook 20 of a horizontal rotary hook 30 provided in a sewing machine frame is configured to detachably store a bobbin thread bobbin 21 through a bobbin thread bobbin storage hole 17. A thread tension bracket and a thread tension spring are attached along the internal circumference of the inner rotary hook 20 with their superposed with each other and functioned as a tension generation part 22 for applying a resistance to a pull-out of the bobbin thread led out through a space between the thread tension bracket and the thread tension spring. Above the inner rotary hook 20, a needle plate 16 having an opening part for taking in/out the bobbin thread bobbin 21 is provided. The needle plate 16 is formed with a guide slit 27 for guiding the bobbin thread, and the guide slit 27 is formed substantially linearly in the extension direction of a superposed part of the thread tension bracket and the thread tension spring. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lower thread supply device for a sewing machine that includes a horizontal hook that detachably accommodates a lower thread bobbin and that can easily set a lower thread during sewing.

  In sewing machines used at home, models that have a horizontal hook that does not need to be installed in a state where the bobbin bobbin is housed in the bobbin case are becoming mainstream instead of the vertical hook. In the case of a sewing machine equipped with a horizontal hook, the lower thread bobbin is simply fitted into the inner hook from the upper opening of the horizontal hook, so that a lower thread supply device is provided so that the lower thread can be reliably supplied.

  For example, in patent document 1, it is comprised so that the cylindrical container-shaped accommodation part of an inner hook may be located under the lower thread bobbin accommodation opening provided in the needle plate. The user accommodates the lower thread bobbin directly from the lower thread bobbin accommodating port so as to be fitted into the inner hook from above. Therefore, it is not necessary to set the lower thread bobbin in the state where the lower thread bobbin is housed in the bobbin case as in the case of using the vertical hook, and the work of setting the lower thread bobbin can be easily performed.

  The lower thread supply device is provided with a tension generating section to give resistance to the lower thread drawn out from the lower thread bobbin. The tension generating portion is attached to a recess formed along a part of the inner peripheral surface of the housing portion of the inner hook in a state where the thread tension plate and the thread tension spring are overlapped. After the user inserts the lower thread bobbin as described above, the user performs an operation of passing the lower thread pulled out from the lower thread bobbin through the tension generating portion. If the sewing machine is operated without the lower thread being properly passed through the tension generating section, the lower thread tension will be weakened, resulting in an excessive supply of lower thread, causing the balance with the upper thread to be lost and making the sewing work well. I can't do it.

  Therefore, in Patent Document 1, a guide member having a plate shape arranged in a substantially horizontal direction is provided above the tension generating portion of the inner hook to guide the lower thread drawn from the lower thread bobbin to the tension generating portion. ing. The lower thread is reliably guided between the thread tension plate and the thread tension spring by moving the drawn lower thread so as to be guided by the guide member provided above the tension generating section, and the tension generating section. Led to. Therefore, the user can set the lower thread by a simple operation of guiding the lower thread pulled out from the lower thread bobbin by the guide member.

Moreover, in patent document 2, the front edge part and side edge part of a needle plate are used as a slit which guides a lower thread, and the front part of a needle plate has a lower thread bobbin accommodation port and the front edge part of a needle plate. A connecting slit is formed to connect the two. When the user winds the bobbin thread from the connecting slit to the front edge and side edge of the needle plate, the bobbin thread is guided between the thread tension plate and the thread tension spring to reach the tension generator. Led. Therefore, the user can set the lower thread by a simple operation of guiding the lower thread pulled out from the lower thread bobbin along the peripheral edge of the needle plate.
JP-A-10-146487 JP 2005-31733 A

  However, in Patent Document 1, it is necessary to provide a separate guide member only for guiding the lower thread, and there is a problem that the structure of the lower thread supply device becomes complicated. In Patent Document 2, although it is not necessary to separately provide a guide member, the shape of the needle plate needs to be processed into an appropriate shape according to the shape and position of the lower thread bobbin. Therefore, in any case, it is difficult to reduce the manufacturing cost, and a simpler structure is required for a household sewing machine that is strongly demanded for price competitiveness.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lower thread supply device for a sewing machine that can reliably supply lower thread with appropriate tension and has a simple structure. .

  In order to achieve the above object, a lower thread supply device for a sewing machine according to a first aspect of the present invention detachably accommodates a lower thread bobbin in an inner hook of a horizontal hook provided in a sewing machine frame through a lower thread bobbin receiving port. The thread tension plate and the thread tension spring are attached so as to overlap each other along the inner periphery of the inner hook, and pass between the thread tension plate and the thread tension spring. In the lower thread supply device of the sewing machine provided with a tension generating section that gives resistance to the withdrawal of the lower thread that is led out, a needle plate having an opening for taking in and out the lower thread bobbin is provided above the inner hook. The needle plate has a guide slit for guiding a lower thread, and the guide slit is formed in a substantially linear shape in the extending direction of the overlapping portion of the thread tension plate and the thread tension spring. .

  In the first invention, the lower thread bobbin can be detachably accommodated in the inner hook of the horizontal hook provided in the sewing machine frame through the lower thread bobbin accommodating port. A thread tension plate and a thread tension spring are attached to the inner hook in a state of being overlapped along the inner circumference thereof, and the lower thread that is led out between the thread tension plate and the thread tension spring. It functions as a tension generator that provides resistance to the pulling out of the wire. A needle plate having an opening through which a lower thread bobbin is taken in and out is provided above the inner hook, and a guide slit for guiding the lower thread is formed in the needle plate. The guide slit is formed in a substantially linear shape in the extending direction of the overlapping portion of the thread tension plate and the thread tension spring, and the user pulls the lower thread on the upper surface side of the inner hook that houses the lower thread bobbin. By moving along the guide slit, the lower thread can be guided to the overlapping portion of the thread tension plate and the thread tension spring, and an appropriate tension is applied to the lower thread. Therefore, without providing a separate guide member, the function of applying an appropriate tension to the lower thread is not impaired, and the needle plate is formed only by a simple manufacturing process of forming a substantially straight slit. A lower thread supply device can be provided, and the manufacturing cost can be reduced.

  The lower thread supply device for a sewing machine according to a second aspect of the present invention is the sewing machine according to the first aspect, wherein the needle plate has a lower length of the lower thread drawn from the lower thread bobbin than a length to the end of the guide slit. It is characterized by comprising a thread trimming part for cutting the lower thread at a predetermined position.

  In the second aspect of the invention, a thread trimming part for cutting the lower thread at a predetermined position of the needle plate is provided so that the length of the lower thread drawn from the lower thread bobbin is longer than the length to the end of the guide slit. If the pull-out length of the lower thread bobbin is too long, there is a high risk that the lower thread and upper thread pulled out at the blade tip of the outer hook will be tangled in a complicated manner. Therefore, the user can easily set the lower thread by ensuring that the lower thread can be cut with an appropriate length.

  According to the present invention, the user moves the lower thread along the guide slit on the upper surface side of the inner hook that houses the lower thread bobbin so that the thread tension plate and the thread tension spring overlap each other. The lower thread can be induced, and an appropriate tension is applied to the lower thread. Therefore, even if a separate guide member is not provided, the function of giving and supplying an appropriate tension to the lower thread is not impaired, and only a simple manufacturing process of forming a substantially linear guide slit on the needle plate is possible. Therefore, it is possible to provide a lower thread supply device for the sewing machine, and it is possible to reduce the manufacturing cost without increasing the number of parts.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. In the following description, the front, rear, left and right viewed from the operator operating the sewing machine will be described as front, back, left and right. FIG. 1 is a perspective view showing an appearance of a sewing machine according to an embodiment of the present invention. As shown in FIG. 1, in the sewing machine according to the embodiment, a sewing table 12 is configured as a part of the sewing machine frame 11, and an arm unit integrated with the sewing machine frame 11 is located above the sewing table 12. 13 is provided. A needle bar 15 to which a sewing needle 14 is attached is provided at the lower end of the arm portion 13, and the needle bar 15 is moved up and down by a known drive mechanism (not shown) to perform sewing.

  A metal needle plate 16 is provided at a portion where the sewing operation is performed facing the needle bar 15. FIG. 2 is a plan view of the needle plate 16 according to the embodiment of the present invention. The needle plate 16 is formed with a needle hole 16a through which the sewing needle 14 passes, and a lower thread bobbin accommodating port 17 that is opened in a rectangular shape is formed on the front side of the needle hole 16a. During normal use, the lower thread bobbin accommodating port 17 is covered with a transparent lid 18 (FIG. 1). Below the needle plate 16 in the sewing machine frame 11 is provided a feed dog mechanism (not shown) for feeding the cloth that is driven as the needle bar 15 moves up and down. A yarn supply device is provided.

  FIG. 3 is a plan view showing the configuration of the lower thread supply device according to the embodiment of the present invention. FIG. 3 is a plan view seen from above in a state where the lid 18 is removed and the lower thread bobbin accommodating port 17 is opened. The lower thread supply device according to the present embodiment is configured by disposing a horizontal hook 30 below the needle plate 16. The horizontal hook 30 is housed in the outer hook 29 that rotates in the horizontal direction in synchronization with the vertical movement of the needle bar 15, and the inner hook 20 provided so as not to rotate in synchronization with the outer hook 29. It consists of and. The outer hook 29 has a sword tip (not shown) for catching the lower thread, and forms a seam by entwining the upper thread with the lower thread in accordance with the vertical movement of the needle bar 15.

  FIG. 4 is a perspective view showing the configuration of the inner hook 20 according to the embodiment of the present invention. As shown in FIG. 4, the inner hook 20 has a substantially cylindrical container shape, and has an accommodation portion 20 a that can accommodate the lower thread bobbin 21 below the lower thread bobbin accommodation port 17. Then, the lower thread bobbin 21 is detachably fitted into the accommodating portion 20a through the lower thread bobbin accommodating port 17. Further, a finger catching recess 20c for taking out the accommodated bobbin thread bobbin 21 is provided on the outer periphery of the accommodating portion 20a.

  The inner hook 20 is provided with a tension generator 22. The tension generating portion 22 is, for example, a screw in a state where the thread tension plate 23 and the thread tension spring 24 are superimposed on an arc-shaped recess 20d formed on a part of the inner peripheral surface of the housing portion 20a of the inner hook 20. 25 and 26 are attached. The thread tension plate 23 and the thread tension spring 24 each have the same arc shape along the recess 20d, and the overlapping portion of the thread tension plate 23 and the thread tension spring 24 is in the housing portion 20a of the inner hook 20. It fits into an arcuate recess 20d on the inner peripheral surface.

  FIG. 5 is a front view of the thread tension plate 23 according to the embodiment of the present invention. As shown in FIG. 5, the thread tension plate 23 has a hole 23a formed in the lower left part, and a slit 23b that is a notch extending obliquely from the center of the upper edge to the lower left and connecting to the hole 23a. Yes. Further, in the vicinity of the hole 23a on the left side of the upper edge, a groove portion 23c for stably pulling out the lower thread guided to the hole 23a from the needle hole 16a of the needle plate 16 is provided.

  The thread tension spring 24 is provided with a step 24a at the right end portion, and a slight gap is formed between the thread tension plate 23 and the thread tension spring 24 at a substantially central portion (a portion near the start end of the slit 23b). Is present, and the left end portion (portion in the vicinity of the hole 23a) is substantially in close contact.

  With this configuration, the lower thread drawn from the lower thread bobbin 21 is guided to the hole 23a along the slit 23b. Therefore, a resistance force is applied to the lower thread by the clamping force between the thread tension plate 23 and the thread tension spring 24, and the lower thread is supplied with an appropriate tension.

  In the present embodiment, as shown in FIGS. 2 and 3, the needle plate 16 is provided with a substantially linear guide slit 27. The inclination angle of the guide slit 27 substantially coincides with the direction circumscribing the lower thread bobbin 21, that is, the direction in which the lower thread is pulled out. Specifically, a guide slit 27 is provided in a direction in which a thread tension plate 23 and a thread tension spring 24 provided in an arc shape on the inner peripheral surface of the inner hook 20 are extended to the main body side. By doing so, the user does not have to be conscious of guiding the lower thread to the groove 23c above the thread tension plate 23, and merely guides the lower thread along the guide slit 27, and the thread tension plate 23 and the thread tension. An appropriate tension is applied to the lower thread through the spring 24.

  The needle plate 16 is provided with a thread trimming portion 28. The thread trimmer 28 guides the lower thread to the cutter 28b at a position where the bottomed groove 28a formed along the outer edge of the needle plate 16 from the end of the guide slit 27 and the length of the lower thread can be sufficiently secured. And a cutter cut portion 28c.

  When using a sewing machine having the above-described lower thread supply device, the user first removes the lid 18 of the sewing table 12 and inserts and sets the lower thread bobbin 21 into the accommodating portion 20a of the inner hook 20. Then, the lower thread is pulled out from the lower thread bobbin 21 and is first hooked on the slit 23 b of the thread tension plate 23.

  Next, the lower thread is rotated clockwise while being hooked on the slit 23 b, and the lower thread is guided in the direction of the guide slit 27 of the needle plate 16. By guiding the lower thread along the direction of the guide slit 27, the lower thread hooked on the slit 23b descends along the slit 23b and is guided to the hole 23a.

  When the lower thread is guided to the hole 23a, the lower thread is in a state where an appropriate tension is applied by the clamping force between the thread tension plate 23 and the thread tension spring 24. The user pulls the lower thread along the guide slit 27 in a state where tension is applied.

  Since the lower thread is guided to the bottomed groove 28 a of the needle plate 16 at the terminal end of the guide slit 27, the bottomed groove formed along the outer edge of the needle plate 16 from the terminal end of the guide slit 27. The lower thread is guided to the cutter 28b along 28a. When the lower thread enters the cutter cut portion 28c, the lower thread is cut by the cutter 28b.

  In this state, the user moves the needle bar 15 up and down by a driving mechanism (not shown). By moving up and down, the outer hook 29 of the horizontal hook 30 rotates horizontally, and the upper thread is entangled with the lower thread captured by the sword tip and pulled out from the needle hole 16a of the needle plate 16 to the upper surface. In this state, the lower thread is drawn from the hole 23a of the thread tension plate 23 of the inner hook 20 to the needle hole 16a through the groove 23c, so that it is not necessary for the user to guide the lower thread to the groove 23c. The upper thread and lower thread that have been pulled out are loosened, and preparations for sewing are complete.

  In the present embodiment, the length of the drawn-out lower thread can be kept substantially constant. Accordingly, there is no possibility that the lower thread pulled out at the sword tip of the outer hook 29 may be entangled with the upper thread in a complicated manner as in the case where the pull-out length from the lower thread bobbin 21 of the lower thread is too long. Further, unlike the case where it is too short, the sword tip of the outer hook 29 does not fail to catch the lower thread, and the user can surely prepare for sewing.

  Thus, according to the present embodiment, the lower thread drawn from the lower thread bobbin 21 is rotated clockwise while being hooked on the slit 23 b on the upper surface side of the inner hook 20, and the guide slit 27 of the needle plate 16 is guided. The lower thread is guided between the thread tension plate 23 and the thread tension spring 24 and passes through the tension generator 22 only by the operation of moving along the thread tension. Therefore, for example, the lower thread can be reliably set without separately providing an arcuate guide member or the like, and since the guide slit 27 is also substantially linear, the number of processing steps can be minimized. Therefore, the manufacturing cost can be reduced.

  Furthermore, in this embodiment, since the thread trimming portion 28 is provided in the needle plate 16, the length of the lower thread drawn from the lower thread bobbin 21 can be made substantially constant, and the length of the drawn length can be shortened. It is also possible to prevent the harmful effects caused by.

  In addition, various modifications to the above-described embodiment within a range not departing from the gist of the present invention, such as a detailed change in the configuration of the tension generator 22, a change in the shape of the thread tension plate 23, a change in the attachment position of the thread trimming part 28, etc. It is possible to implement with the form which added.

It is a perspective view which shows the external appearance of the sewing machine which concerns on embodiment of this invention. It is a top view of a needle plate concerning an embodiment of the invention. It is a top view which shows the structure of the bobbin thread supply apparatus which concerns on embodiment of this invention. It is a perspective view which shows the structure of the inner hook which concerns on embodiment of this invention. It is a front view of the thread tension board which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Sewing machine frame 16 Needle plate 17 Lower thread bobbin accommodation port 20 Inner hook 21 Lower thread bobbin 22 Tension generating part 23 Thread tension plate 24 Thread tension spring 27 Guide slit 28 Thread trimming part 29 Outer hook 30 Horizontal hook

Claims (2)

The lower thread bobbin can be detachably accommodated in the inner hook of the horizontal hook provided in the sewing machine frame through the lower thread bobbin receiving port.
Pulling out a lower thread that is attached in a state where a thread tension plate and a thread tension spring are overlapped along the inner circumference of the inner hook, and is led out between the thread tension plate and the thread tension spring. In the lower thread supply device of the sewing machine provided with a tension generating part that gives resistance to
Above the inner hook, comprising a needle plate having an opening for taking in and out the lower thread bobbin,
The needle plate has a guide slit for guiding the lower thread,
The lower thread supply device for a sewing machine, wherein the guide slit is formed in a substantially linear shape in the extending direction of the overlapping portion of the thread tension plate and the thread tension spring.   The needle plate includes a thread trimming unit that cuts the lower thread at a predetermined position where the length of the lower thread drawn from the lower thread bobbin is longer than the length to the end of the guide slit. The lower thread supply device of the sewing machine according to claim 1.

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