JPS5931356B2 - Sewing machine bobbin thread tension generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bobbin thread tension generating device for a sewing machine.

Conventionally, bobbin thread tension in sewing machines is generated by a plate attached to the inner pot or bobbin case that pinches the bobbin thread, and the bobbin thread tension is adjusted by tightening the screw that tightens the leaf spring. It is done by doing.

However, as is well known, since the upper thread passes around the inner hook, it has been impossible to adjust the lower thread tension while the sewing machine is sewing.

Therefore, in the past, to adjust the bobbin thread tension, it was necessary to perform a trial stitch, stop the sewing machine, adjust the bobbin thread tension, and then repeat the process of trial sewing to adjust the appropriate bobbin thread tension. However, it was time-consuming and troublesome.

Sewing machines that automatically adjust the needle thread tension have also been devised, but the thread tension of the sewing machine requires adjusting both the needle thread tension and the bobbin thread tension. It has been impossible to automatically adjust the thread tension for thin fabrics.

The present invention was made to solve the above problems,
A lower thread tension applying means that is operated by magnetic force and applies tension to the lower thread according to the strength of the magnetic force is provided on the inner hook side of the sewing machine, and a magnetic force that applies magnetic force to the lower thread tension applying means is provided outside the inner hook. The lower thread tension is adjusted by providing a applying means and changing the strength of the magnetic force applied by the magnetic force applying means to the lower thread tension applying means, and the lower thread tension can be adjusted even during sewing with the sewing machine. This makes it possible to easily adjust the thread tension.

Furthermore, by automating the upper and lower thread tension generator in combination with the upper thread tension generator, it is possible to automatically adjust the optimum thread tension for various types of fabrics.

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 are cross-sectional views of strips showing first to fifth embodiments of the present invention, respectively.

In FIG. 1, an outer hook 1 is pivotally supported on a machine frame 2 of the sewing machine,
It is adapted to be rotated by a driving source (not shown) of the sewing machine.

Reference numeral 3 denotes a plastic inner pot, which is inserted into the outer pot 1 and fixed to prevent rotation by a hook stopper (not shown).

4 is a bobbin housed in the inner hook 3 and wound with a bobbin thread.

Further, a hollow portion 1a is provided in the rotating shaft of the outer hook 1, and the hollow portion 1
Inside a, an electromagnet 5 fixed to the sewing machine frame 2 is provided so as to face a suction portion 6a of an operating body 6 of the inner hook 3, which will be described later.

An operating body 6 made of a magnetic material that cooperates with the electromagnet 5 is attached to the inner pot 3, and the operating body 6 is swingably supported by the inner pot 3 at a fulcrum 6b at its center, and its lower end is attached to an adsorbent. The portion 6a faces the electromagnet 5.

Further, the upper end of the operating body 6 is a dish-shaped bobbin thread holding portion 6C,
The bobbin thread 7 from the bobbin 4 is sandwiched between the bobbin thread 7 and the opposing wall surface 3a of the inner hook 3, and the bobbin thread tension is generated by friction.

Therefore, by passing a current through the electromagnet 5, a magnetic force is generated, and the feeding portion 6a of the actuating body 6 is attracted in the direction of the electromagnet 5.
The actuating body 6 rotates around a fulcrum 6b, and the bobbin thread holding part 6c is pressed toward the wall surface 3a of the inner hook 3, and the bobbin thread 7 held between the bobbin thread holding part 6C and the wall surface 3a is pressed. Tension is generated due to frictional force.

That is, since the lower thread tension applying means in the inner hook 3 is operated without contact by magnetic force from outside the inner hook 3, the upper thread can pass around the inner hook 3, and even during sewing with the sewing machine. By changing the magnitude of the current applied to the electromagnet 5, it becomes possible to freely adjust the bobbin thread tension.

Although the operating member of the current control device for the electromagnet 5 is not shown, it can be freely placed on the machine frame of the sewing machine or the like.

Next, a second embodiment shown in FIG. 2 will be described.

In this embodiment, a pair of opposing permanent magnets 8 and 9 are used as lower thread tension applying means in place of the operating body 6 of the first embodiment.

That is, a first permanent magnet 8 is fixed to the bottom 3b of the inner pot 3 so as to face the electromagnet 5, and a second permanent magnet 9 is installed inside the inner pot 3 above the first permanent magnet 8. , 9 are arranged so that the same polarities face each other.

When the electromagnet 5 is not energized, the second permanent magnet 9 is repelled by the first permanent magnet 8 and is pressed against the inner wall surface 3c of the inner pot 3, so that an appropriate gap is left between the two permanent magnets 8. I have to.

The bobbin thread 7 is led from the bobbin 4 to the outside of the inner hook 3 through between the two permanent magnets 8 and 9, and by passing current through the electromagnet 5, the repulsive force between the two permanent magnets 8 and 9 is reduced. A strong attractive force is applied to the permanent magnet 9, and the permanent magnet 9 is connected to the electromagnet 5.
The lower thread 7 is held between both permanent magnets 8 and 9 to generate lower thread tension.

The bobbin thread tension can be adjusted by the current applied to the electromagnet 5 as in the first embodiment.

Further, in this embodiment, when the electromagnet 5 is not energized, the permanent magnets 8 and 9 repel each other and a gap is formed between the permanent magnets 8 and 9, so that when the bobbin thread 7 is attached, the thread is It has the advantage of being easy to pass through.

A third embodiment shown in FIG. 3 uses a movable permanent magnet 10 as a magnetic force applying means in place of the electromagnet 5 of the first embodiment.

That is, a shaft 11 fixed to the machine frame 1 is provided in the hollow part 1a of the outer hook 1, a permanent magnet 10 is loosely fitted onto the shaft 11 so as to be movable up and down, and a lever 12 is applied to the permanent magnet 10. , the permanent magnet 10 can be moved along the axis 11 using a lever 12.

That is, by moving the permanent magnet 10 with the lever 12, the distance between the permanent magnet 10 and the attraction part 6a of the operating body 6 is changed, thereby changing the strength of the magnetic force on the operating body 6, thereby increasing the bobbin thread tension. It is something to be adjusted.

Further, in the fourth embodiment shown in FIG. 4, the magnetic force applying means is arranged in the lateral direction of the inner pot 3.

A rotating shaft 13 is fixed to the outer hook 1, and the rotating shaft 13 is pivotally supported by the machine frame 2.

Further, like the previous example, an inner hook 3 is inserted into the outer hook 1, and a bobbin 4 on which a bobbin thread 7 is wound is housed inside the inner hook 3.

A permanent magnet 15 movably fixed to the inner hook 3 by a spring 14 is provided inside the inner hook 3 on the side of the bobbin 4, and an electromagnet 5 fixed to the machine frame 2 is installed outside the inner hook 3. The permanent magnets 15 are arranged close to each other.

The lower thread 7 comes out of the bobbin 4, passes between the inner wall surface 3e of the inner hook facing the permanent magnet 15, and the permanent magnet 15, and is guided to the outside.

Then, by passing a current through the electromagnet 5, the permanent magnet 15 is repelled in the direction of the inner wall surface 3e by magnetic force, and the inner wall surface 3e is repelled by the magnetic force.
This applies tension due to friction to the lower thread 7 held between the permanent magnet 15 and the lower thread 7.

In this embodiment, since the magnetic force applying member is arranged in the lateral direction of the inner pot 3, there is an advantage that the structure is simpler than that in the above example in which the magnetic force imparting member is arranged in the downward direction of the inner pot.

Incidentally, although the embodiments relate to a horizontal pot, the present invention is not limited to a horizontal pot, and can of course be applied to a vertical pot.

Further, the material of the inner pot is preferably a non-magnetic material such as plastic, but it may also be made of a magnetic material.

As described above, since the present invention adjusts the lower thread tension by adjusting the magnetic force applied from the outside of the inner hook, it is possible to freely adjust the lower thread tension even during sewing with the sewing machine. This not only simplifies the task of adjusting thread tension during sewing work on a sewing machine, but also automates upper and lower thread tension adjustment in combination with an upper thread tension generator.
This invention makes it possible to automatically adjust the thread tension of a sewing machine and has a simple structure, making it an industrially useful invention.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views of the strips of the embodiment of the present invention. 1... Outer pot, 2... Sewing machine frame, 3.
...Inner pot, 4...Bobbin, 5...
・Electromagnet, 6... Working body, 7... Lower thread, 8, 9, 10.15... Permanent magnet, 14...
...Spring.

Claims (1)

[Claims] 1. A lower thread tension applying means that is operated by magnetic force and applies tension to the lower thread pulled out from the bobbin according to the strength of the magnetic force is provided on the inner hook side of the sewing machine, and a magnetic force is applied to the lower thread tension applying means. A lower thread tension generating device for a sewing machine, characterized in that a magnetic force applying means is provided outside the inner hook, and the lower thread tension is adjusted by changing the strength of the magnetic force applied by the magnetic force applying means to the lower thread tension applying means. .