JPH07144080A - Rotary bobbin for sewing machine - Google Patents

Abstract

PURPOSE:To provide the rotary bobbin for sewing machine so as to smoothly move an upper thread loop along the periphery of a middle bobbin even without using any opener. CONSTITUTION:The rotary bobbin for sewing machine is provided with an outer bobbin 12 fixed to a bobbin shaft 11, middle bobbin 13 freely turnably fitted to this outer bobbin, and lock members 15 and 16 for regulating the turning range of this middle bobbin, and a rotational center of the middle bobbin is made eccentric to a rotational center 11C of the bobbin shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary hook of a sewing machine in which an outer hook and an inner hook are rotatably fitted to each other, and more particularly,
The present invention relates to a rotary hook of a sewing machine in which an upper thread loop can be smoothly moved along the circumference of an inner hook.

[0002]

2. Description of the Related Art Generally, as a rotary hook of a sewing machine, a rotary hook shown in FIG. 10 is known. The rotary hook is composed of an outer hook 2 fixed to a hook shaft 1 that rotates in synchronization with the lifting and lowering operation of a sewing needle, and an inner hook 3 rotatably fitted to the outer hook. A lower thread bobbin (not shown) having a lower thread wound thereon is rotatably held therein. The rotation center 3C of the inner hook 3 coincides with the rotation center 1C of the hook shaft 1. Further, an engaging protrusion 3a protruding outward is formed on a peripheral portion of the inner hook 3, and the engaging protrusion 3a is provided on a lower surface of the needle plate 4 so as to project from a pair of locking members 5 and 6. It is loosely fitted in between.

In the rotary hook of the sewing machine constructed as described above, when the sewing machine is driven and the hook shaft 1 rotates, the inner hook 3
The friction with the outer hook 2 always applies a force to rotate in the same direction as the outer hook 2. Therefore, if an external force is not applied to the inner hook 3 other than this rotational force, the engagement protrusion 3a of the inner hook 3 will continue to be joined to one of the locking members 5, but this The upper thread loop passing around the shuttle 3 cannot pass between the engaging projection 3a and the locking member 5, and a large tension is applied to the upper thread loop, which hinders the stitch forming operation.

For this reason, the movable member 7 conventionally referred to as an opener forcibly urges the inner hook 3 in the opposite direction (the direction opposite to the urging direction of the outer hook), so that the engaging projection 3a is locked. The upper thread loop caught by the outer hook 2 moves through the above-mentioned interval so that a large tension is not applied to the upper thread loop.

[0005]

As described above, in the conventional rotary hook of the sewing machine, the opener 7 is used to rotate the inner hook against the rotational force of the outer hook. Various components such as a cam are required to operate the sewing machine 7, which has been a factor of increasing the cost of the sewing machine. Further, since the opener 7 generates a large impact sound when it comes into contact with the inner hook 3, there is a problem that the working environment at the sewing site is deteriorated, and various proposals have been made to solve this problem. Is.

The present invention has been made in view of the above-mentioned problems of the prior art. A rotary hook of a sewing machine in which the upper thread loop can be smoothly moved along the circumference of the inner hook without using an opener. For the purpose of provision.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to an outer hook fixed to a hook shaft that rotates in synchronization with a lifting operation of a sewing needle, an inner hook rotatably fitted to the outer hook, and an inner hook. A rotary hook of a sewing machine provided with a locking member for restricting a rotation range of the inner hook, wherein a center of rotation of the inner hook is biased with respect to a center of rotation of a hook shaft.

[0008]

In the present invention, the rotation of the outer hook causes a rotational force about the center of rotation of the hook shaft to be applied to the inner hook, but the center of rotation of the inner hook is deviated from the center of rotation of the hook shaft. , The contact portion of the inner hook makes a rocking motion for each sewing cycle with respect to the locking portion that restricts the rotation of the inner hook, and when the contact portion is separated from the locking portion, the upper thread loop is not connected to the inner hook. Since it passes through between the locking member, it is possible to perform an appropriate stitch forming operation without using an opener.

[0009]

Embodiments of the present invention will be described below. 1 to 6 are views showing a first embodiment of the present invention. In each drawing, reference numeral 11 denotes a shuttle shaft rotatably supported by the shuttle shaft base. The shuttle shaft 11 is connected via a gear or the like to a sewing machine lower shaft (not shown) that rotates in synchronization with the sewing machine main shaft, and is rotated in synchronization with the lifting and lowering operation of the sewing needle. Further, an outer hook 12 is provided at the upper end of the hook shaft 11 so that it can rotate integrally with the hook shaft 11.

The outer hook 12 in this embodiment is formed with a sword tip 12a for catching the upper thread loop, and the race surface 1 for rotatably fitting the inner hook 13 therein.
2b is formed. This race surface has an arc shape,
The shape of itself is similar to the race surface of the conventional outer hook, but the forming position is different from the conventional one. That is,
While the race surface 12b of the conventional outer hook 12 is formed concentrically with the center axis 1C of rotation of the hook shaft, the center 12d of the race surface 12b in this embodiment is the hook as shown in FIGS. It is set at a position deviated from the center 11C of the shaft 11, which is different from the conventional one. At this time, the center 12C of the outer circumference 12e of the outer hook and the center 11 of the hook shaft 11
C is formed concentrically.

The offset position of the center 12d of the race surface 12b is within the range indicated by Z in FIG. 1, and the range is defined as follows. First, the tip of the sword tip 12a and the center of the shuttle shaft 1
Draw a straight line through 1C. Next, the straight line is rotated counterclockwise by 120 degrees about the center 11C of the shuttle shaft 11 as the center of rotation. Further, Z is a range in which the rotated straight line is rotated 90 degrees in the clockwise direction and 90 degrees in the counterclockwise direction with the center 11C of the shuttle shaft 11 as the center of rotation.

On the other hand, the inner hook 13 has the race surface 12b.
It is rotatably fitted in. For this reason, the center 13C of rotation of the inner hook 13 is biased with respect to the center 12C of the outer hook as shown in FIG. 5, and as a result, it is also biased with respect to the center 11C of rotation of the hook shaft 11. Further, an engagement protrusion 13a as an abutting portion is formed on the peripheral portion of the inner hook 13, and this engages loosely between the locking members 15 and 16 projectingly provided on the lower surface of the needle plate 14, The members 15 and 16 can be selectively brought into contact with each other. It should be noted that, unlike the conventional inner pot 3 shown in FIG. 10, the peripheral portion of the inner pot 13 in this embodiment is not formed with a protruding portion 3b for contacting the opener 7, so that the shape is simplified. Has been planned.

The rotary hook of the sewing machine in this embodiment is constructed as described above. When the sewing machine is driven and the sewing needle starts to move up and down by the rotation of the sewing machine main shaft, the hook shaft 1
The outer hook 12 rotates together with 1, and the sword tip 12a catches and pulls out the upper thread loop formed below the needle plate 14,
Pass around 3 and knot with bobbin thread. Then, in such a sewing operation, a rotational force in the rotational direction about the shuttle shaft 11 is applied to the inner shuttle 13 by the frictional force with the outer shuttle 12. At the beginning of one sewing cycle, the inner hook 13
Since the rotation center 13C of the inner hook 13 is located to the left of the rotation center 11C of the hook shaft 11, the engaging protrusion 13a of the inner hook 13 abuts on the locking member 16 and the right locking member 15 by the biasing force. A gap g1 is formed between and (see FIG. 6).
(See (a)). Therefore, the upper thread loop captured by the sword tip starts to move smoothly around the inner hook 13 by passing through the gap g1.

After this, the center of rotation of the inner hook 13 is shown in FIG. 6 (b).
After passing through the intermediate position shown in FIG.
When it moves to the right side, the engaging protrusion 13a of the inner hook 13 comes into contact with the right locking member 15, so that the left locking member 16
A gap g2 is formed between and. Therefore, the inner pot 13
The upper thread loop that has moved around the area passes through this gap g2 and is smoothly removed from the inner hook 13 to be knotted with the lower thread.

As described above, in this embodiment, unnecessary rotation of the inner hook 13 can be prevented by the engaging projection 13a and the locking members 15 and 16, and the engaging projection 13a can be engaged without using the opener. Gap between the stopper 15
Since 1 and g2 can be appropriately and selectively formed, the upper thread loop can be smoothly passed through the inner hook 13. Therefore, it is possible to omit all the components that have been required to configure the opener up to now, and it is possible to significantly reduce the cost of the sewing machine. Further, since there is no impact sound from the opener, the noise level at the sewing site is reduced and the working environment is significantly improved.

Next, a second embodiment of the present invention will be described with reference to FIG. The same or corresponding parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, as in the first embodiment, the center of rotation of the inner hook 13 with respect to the outer hook 12 is biased with respect to the center of rotation of the hook shaft 11, while a fixing member 17 is provided on the machine frame to dispose the middle member. By contacting the protrusion 13b formed on the peripheral portion of the shuttle 13, the rotation of the inner shuttle when the sewing machine is driven can be prevented. In this embodiment as well, the engaging projection 13a is provided as a contact portion in the same manner as in the above embodiment.

According to this embodiment, a sufficient gap g1 is constantly formed between the engaging member 15 and the engaging projection (contact portion) 13a where the upper thread loop is most likely to be caught when passing through the inner hook 13. Therefore, the movement of the upper thread loop can be further stabilized. In addition, the needle thread loop is in the inner hook 13.
In order to disengage from the engaging projection 13a and the fixing member 17,
It is necessary to form gaps g2, g3 for passing the upper thread loop between the protrusion 13b of the inner hook 13 and the fixing member 17, respectively. Similarly, since it is selectively formed by the rotary swing motion of the inner hook 13 with respect to the outer hook 12, the movement of the upper thread loop is not hindered.

In the second embodiment, the locking member 15
However, in this embodiment, since the locking member 17 restricts the rotation of the inner hook 13 in the direction of the inner hook 13, one locking member 15 may be omitted. Is.

FIG. 8 is a diagram showing a third embodiment of the present invention. In the third embodiment, the center of rotation of the inner hook 13 and the center of rotation of the hook shaft are deviated in the same manner as in the above embodiments, while the fixing member 27 having a recess 27a is formed on the side of the rotary hook.
Is provided as a hooking member, and a projecting portion 23a having a shape that can be loosely inserted into the recess 27a is formed in the inner hook. The projecting portion 23a is formed along with the rotation of the outer hook.
By selectively abutting both end faces 27a1 and 27a2 of the above, the upper thread loop can be smoothly passed. In this embodiment, since the locking members 15 and 16 and the engaging projections 13a in the first and second embodiments are not necessary, the needle plate 14 and the inner hook can be simplified in shape.

Further, as shown in FIG. 4, in the first to third embodiments, the outer hook 12 provided concentrically with the hook shaft 11 is provided.
On the other hand, the inner hook 13 and the outer hook 11 are made eccentric by eccentrically moving the inner hook 13 and the inner hook 13 and the outer hook 1.
2 can be provided concentrically and the hook shaft 11 and the outer hook 12 can be eccentric to obtain the same effect.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, the center of rotation of the inner hook 13 and the center of rotation of the hook shaft are made to coincide with each other, and a weight 30 is attached to a flat surface portion of the inner hook 13.
The latch members 15, 16 and the like are the same as in the first embodiment. According to this embodiment, since the center of gravity of the inner hook 13 and the center of gravity of the hook shaft are deviated by the weight 30, the engaging projection 13a of the inner hook 13 is rotated with the rotation of the hook shaft as in the above embodiments.
Comes into contact with the latch members 15 and 16 selectively,
This allows the upper thread loop to be smoothly pulled out from the inner hook.

[0022]

As described above, in the rotary hook of the sewing machine according to the present invention, the center of rotation of the inner hook or the center of gravity of the inner hook is deviated from the center of rotation of the hook shaft for holding the outer hook. A gap can be appropriately formed between the locking member that restricts the rotation range of the hook and the contact portion of the inner hook, and the upper thread loop can be smoothly passed around the inner hook by passing through the gap. Can be moved along with. This eliminates the need for an opener, which has been indispensable for sewing machines, simplifies the mechanism of the sewing machine, and greatly reduces the cost, and can completely eliminate the impact sound generated by the opener. Next to
It is expected that the working environment at the sewing site will be improved, and the effect will be enormous.

[Brief description of drawings]

FIG. 1 is a plan view showing the shape of an outer pot 12 in a first embodiment of the present invention.

FIG. 2 is a side view of what is shown in FIG.

3 is a perspective view of what is shown in FIG. 1. FIG.

[FIG. 4] An inner hook 13 and an outer hook 12 are concentrically provided, and a hook shaft 11 is provided.
And another embodiment in which the outer pot 12 is eccentric.

FIG. 5 is an explanatory plan view showing a fitted state of the outer hook 12 and the inner hook 13 in the first embodiment of the present invention.

FIG. 6 is an explanatory plan view of the above embodiment showing changes in the positional relationship between the inner hook 13 and the locking member in one sewing cycle.

FIG. 7 is an explanatory plan view showing a second embodiment of the present invention.

FIG. 8 is a plan view showing a third embodiment of the present invention.

FIG. 9 is a plan view showing a fourth embodiment of the present invention.

FIG. 10 is a plan view showing a rotary hook of a conventional sewing machine.

[Explanation of symbols]

 11 hook shaft 11C rotation center of hook shaft 12 outer hook 12C center with respect to outer circumference of outer hook 12d center of race surface of outer hook 13 inner hook 13a engaging protrusion (contact portion) 13b protruding portion (contact portion) 13C inner hook Center of rotation 15 Locking member 16 Locking member 17 Locking member 27 Fixing member (locking member) 23a Projection part (contact part) 30 Weight

Claims (2)

[Claims] 1. An outer hook which is fixed to a hook shaft which rotates about a vertical axis in synchronization with the vertical movement of a sewing needle and which rotates integrally with the hook shaft, and is rotatably fitted to the outer hook. And a locking member that can be brought into and out of contact with a predetermined contact portion of the inner hook. The rotation range of the inner hook is regulated by the contact between the contact portion and the locking member. A rotary rotary hook of a sewing machine, wherein the center of rotation of the inner hook is biased with respect to the center of rotation of the hook shaft. 2. An outer hook that is fixed to a hook shaft that rotates about a vertical axis in synchronization with the vertical movement of a sewing needle and that rotates integrally with the hook shaft, and is rotatably fitted to the outer hook. And a locking member that can be brought into and out of contact with a predetermined contact portion of the inner hook. The rotation range of the inner hook is regulated by the contact between the contact portion and the locking member. A horizontal rotary hook of a sewing machine, wherein the center of rotation of the inner hook and the center of gravity of the inner hook are offset from each other.