JP5810620B2 - Sewing thread tension device and sewing machine - Google Patents

Description

  The present invention relates to a sewing thread tension device and a sewing machine.

  Patent Document 1 shows a sewing thread tension device that adjusts thread tension. The device includes a first thread tension tray, a second thread tension tray, a thread tension spring having a spring force for adjusting the thread tension by urging the second thread tension tray toward the first thread tension tray, A thread tension dial that adjusts the degree of strength of the spring tension of the thread tension spring, a spring force adjustment cam that is provided on the thread tension dial and that can adjust the thread tension spring, and a thread tension spring that moves following the spring force adjustment cam. And a first adjustment member that is screwed onto the transmission plate and receives the other end of the thread tension spring.

  Patent Document 2 shows a sewing thread tension device that adjusts thread tension. This device has a thread tension dial that adjusts the tension acting on the upper thread, and a spring force adjustment cam that is formed on the thread tension dial and can adjust the spring force of the thread tension spring. A user can obtain a desired tension by manually rotating the thread tension dial.

JP 2008-264065 A JP-A-6-154454

  In order to obtain a desired thread tension according to the sewing product, it is necessary for the user to change the thread tension by manually rotating the dial. When the thickness of the sewing product is thin, it is preferable to reduce the thread tension. When the sewing product is thick, it is preferable to increase the thread tension. In order to increase the thread tension, it is preferable to increase the spring constant of the thread tension spring. However, when the spring constant of the thread tension spring is increased, the rotational torque of the thread tension dial increases, and the user feels that the rotation operation of the thread tension dial is heavy and feels uncomfortable with the rotation operation of the thread tension dial. Increasing the diameter of the thread tension dial reduces the uncomfortable feeling of rotation of the thread tension dial, but considering the design of the sewing machine, there is a limit to increasing the diameter of the thread tension dial.

  The present invention has been made in view of the above circumstances, and even when the spring constant of the thread tension spring is increased, the spring force of the thread tension spring is suppressed while suppressing an increase in the diameter of the thread tension dial. It is an object to provide a sewing thread tension device and a sewing machine that are advantageous for fine adjustment.

(1) A sewing thread tension device according to aspect 1 of the present invention is a sewing thread tension device that is provided in a sewing machine and adjusts the thread tension, and includes (i) a first thread tension tray, and (ii) a first thread tension. A second thread tension tray facing the first thread tension tray so as to sandwich the thread with the tray; and (iii) the second thread tension tray in the direction in which the first thread tension tray and the second thread tension tray approach each other. (Iv) A thread tension spring having a spring force for adjusting the thread tension by urging the thread tension plate, and (iv) movable along a spring force adjustment direction for adjusting the strength of the spring tension of the thread tension spring. A movable body, (v) a cylindrical portion, a conversion mechanism for moving the movable body along the spring force adjustment direction along with the rotation, and a rotation center on the inner peripheral wall of the cylindrical portion. A rotating body having a plurality of internal teeth formed with a predetermined pitch circle diameter with respect to (vi) A plurality of external teeth provided so as to be rotatable with respect to the rotating body by a rotating operation of the user and formed with a pitch circle diameter Dout smaller than the pitch circle diameter Din of the internal teeth of the rotating body and capable of meshing with the internal teeth of the rotating body And a thread tension dial for transmitting the rotation so as to reduce the rotation speed of the rotating body by meshing the external teeth and the internal teeth with the rotation and rotating the rotating body in a common direction. To do.

  When the rotating body is rotated, the rotating body moves the movable body along the spring force adjusting direction by the conversion mechanism. As a result, the degree of strength of the spring force of the thread tension spring is adjusted, the force for pinching the thread between the first thread tension tray and the second thread tension tray is adjusted, and the thread tension is adjusted accordingly.

When the thread tension dial is rotated by the user, the external teeth rotate with the thread tension dial. Then, the internal teeth that mesh with the external teeth of the single rotation rotate around the rotation center of the rotating body. Here, the pitch circle diameter Dout of the external teeth of the thread tension dial is made smaller than the pitch circle diameter Din of the internal teeth of the rotating body. Therefore, the number Nout of external teeth is made smaller than the number Nin of internal teeth of the rotating body. Therefore, the thread tension dial serves as a drive source, and when the external teeth of the thread tension dial mesh with the internal teeth of the rotating body, a speed reduction mechanism is configured. Therefore, when the user rotates the thread tension dial, the rotation speed of the thread tension dial can be reduced and transmitted to the rotating body. When the rotating body is rotated as described above, the rotation of the rotating body moves the movable body along the spring force adjusting direction by the conversion mechanism, thereby adjusting the degree of the spring force of the thread tension spring. The force for pinching the thread between the first thread tension tray and the second thread tension tray is adjusted, and consequently the thread tension is adjusted.

  According to the present invention as described above, when the thread tension dial serves as a drive source and the external teeth of the thread tension dial mesh with the internal teeth of the rotating body, the speed reduction mechanism is configured, so the strength of the spring force of the thread tension spring is increased. Thus, the force for pinching the yarn between the first thread tension plate and the second thread tension plate can be finely adjusted, and the yarn tension can be finely adjusted. In this case, it is possible to efficiently adjust the degree of strength of the spring force of the thread tension spring as compared with the case where the speed reduction mechanism is not provided, that is, when the user directly rotates the rotating body. .

  By the way, in order to obtain from a small thread tension to a large thread tension, it is preferable to use a thread tension spring having a high spring constant as much as possible. Further, when the thickness of the material to be sewn such as cloth is thick, it is preferable to increase the spring constant of the thread tension spring in order to increase the thread tension. However, in this case, the rotational torque of the thread tension dial operated by the user increases. Further, even if the thread tension dial is operated by a small amount of rotation, the degree of fluctuation of the strength of the spring tension spring becomes large, and it is not always easy to finely adjust the degree of spring tension of the thread tension spring. That is, it is not always easy to finely adjust the force for pinching the yarn between the first thread tension plate and the second thread tension plate. As a result, it is not always easy to finely adjust the thread tension. In this regard, according to the present invention, when the thread tension dial becomes a drive source and the external teeth of the thread tension dial mesh with the inner teeth of the rotating body, the speed reduction mechanism is configured. It is possible to finely adjust the degree, finely adjust the force for pinching the yarn between the first and second thread tension plates, and finely adjust the yarn tension. In this case, even if the spring constant of the thread tension spring is high, the thread tension spring of the thread tension spring is smaller than when the speed reduction mechanism is not provided, that is, when the user directly rotates the rotating body. The degree of strength of the spring force can be adjusted efficiently.

  (2) According to the sewing thread tension device according to aspect 2 of the present invention, in the above aspect, the thread tension dial is provided coaxially with the outer cylinder portion rotated by the user and the outer cylinder portion. It has the gear formed with the inner cylinder part which has this, It is characterized by the above-mentioned. In this case, if the user rotates the thread tension dial, the external teeth of the thread tension dial and the inner teeth of the rotating body mesh with each other, and the speed reduction mechanism is configured. Therefore, the position of the movable body can be finely adjusted. For this reason, it is advantageous to finely adjust the strength of the spring force of the thread tension spring, to finely adjust the force between the first thread tension tray and the second thread tension tray, and to finely adjust the thread tension. It becomes.

(3) According to the sewing thread tension device according to aspect 3 of the present invention, in the above aspect, the thread tension dial is provided such that the rotation center thereof is eccentric with respect to the rotation center of the rotating body, A shaft end surface as a connecting portion for connecting the inner cylinder portion is provided on the rotating body side, and the shaft end surface has a concealing surface portion concealed by the rotating body and an exposed surface portion exposed from the rotating body. . In this case, since the rotation center of the thread tension dial is decentered with respect to the rotation center of the rotating body, the user can be prevented from confusing the thread tension dial and the rotating body visually or operationally. If a display portion for adjusting the degree of the strength of the thread tension is formed on the shaft end surface of the thread tension dial, the user can visually recognize the display portion of the exposed surface portion of the thread tension dial.

  (4) According to the sewing thread tension device according to aspect 4 of the present invention, in the aspect described above, the shaft end surface of the thread tension dial is provided with a display portion that indicates the degree of strength of the thread tension. The direction of the display unit indicating the degree and the rotation direction of the thread tension dial are common. Along with the rotation operation of the thread tension dial by the user, the shaft end surface of the thread tension dial can be switched from the concealed surface portion concealed by the rotating body to the exposed surface portion exposed from the rotating body. For this reason, if the display part which shows the degree of the strength of the thread tension is formed on the shaft end face of the thread tension dial, the user can visually recognize the display part displayed on the exposed surface part, and the thread tension The degree of strength can be visually recognized on the display unit. In this case, since the direction of the display unit indicating the degree of yarn tension strength and the rotation direction of the thread tension dial are common, the user can adjust the strength of the yarn tension without feeling uncomfortable.

(5) The sewing machine according to aspect 5 of the present invention is a sewing machine including a sewing thread tension device that adjusts the thread tension, and the sewing thread tension device includes (i) a first thread tension plate, (ii) a first A second thread tension tray facing the first thread tension tray so as to sandwich the thread with the thread tension tray; and (iii) a second thread tension tray in a direction in which the first thread tension tray and the second thread tension tray approach each other. A spring tension spring having a spring force for adjusting the thread tension by urging the thread tension toward the first thread tension plate, and (iv) a spring force adjusting direction for adjusting the degree of strength of the spring tension of the thread tension spring. A movable body movable; (v) provided in a rotatable manner around the center of rotation; a cylindrical portion; a conversion mechanism for moving the movable body along the direction of spring force adjustment with rotation; and an inner peripheral wall of the cylindrical portion. A rotating body having a plurality of internal teeth formed with a predetermined pitch circle diameter with respect to the rotation center; vi) A plurality of outer surfaces which are provided so as to be rotatable with respect to the rotating body by a rotation operation of the user, are formed with a pitch circle diameter Dout smaller than the pitch circle diameter Din of the inner teeth of the rotating body and can mesh with the inner teeth of the rotating body. A thread tension dial having teeth and transmitting the rotation to rotate the rotating body in a common direction so as to reduce the rotation speed of the rotating body by meshing of the external teeth and the internal teeth with the rotation. And

  The same action as in aspect 1 is obtained. That is, when the user rotates the thread tension dial and the thread tension dial serves as a drive source and the external teeth of the thread tension dial mesh with the inner teeth of the rotating body, the reduction mechanism is configured, so the spring force of the thread tension spring It is possible to finely adjust the degree of strength of the thread, finely adjust the force between the first and second thread tension plates, and finely adjust the thread tension. In this case, even if the spring constant of the thread tension spring is high, the thread tension spring of the thread tension spring is smaller than when the speed reduction mechanism is not provided, that is, when the user directly rotates the rotating body. The degree of strength of the spring force can be adjusted efficiently.

  According to the present invention, when the user rotates the thread tension dial and the external teeth of the thread tension dial mesh with the internal teeth of the rotating body, the speed reducing mechanism is configured, so that the position of the movable body can be finely adjusted. It is possible to finely adjust the degree of strength of the thread tension spring, and thus finely adjust the degree of strength of the thread tension. Since the speed reduction mechanism is provided in this way, when the spring constant of the thread tension spring is higher than when the speed reduction mechanism is not provided, that is, when the user directly rotates the rotating body. Even so, the strength of the spring force of the thread tension spring can be adjusted efficiently. Moreover, the torque for rotating the thread tension dial can be reduced, and the user is prevented from feeling heavy on the thread tension dial.

  Furthermore, according to the present invention, even when the spring constant of the thread tension spring is high, compared to the case where the speed reduction mechanism is not provided, that is, compared to the case where the user directly rotates the rotating body, Since the torque for rotating the thread tension dial can be kept small, the strength of the spring force of the thread tension spring can be adjusted efficiently.

It is a perspective view of a thread tension device. It is a figure which shows the meshing state of the internal tooth of the rotary body of a thread tension device, and the external tooth of a thread tension dial. It is a figure which shows typically the conversion mechanism of a rotary body. It is a front view of the sewing machine which shows an application form and has a thread tension device.

  The first thread tension tray and the second thread tension tray adjust the thread tension with the thread interposed therebetween. The thread tension spring has a spring force that adjusts the thread tension by urging the second thread tension tray toward the first thread tension tray in a direction in which the first thread tension tray and the second thread tension tray approach each other. The movable body is movable along a spring force adjustment direction for adjusting the degree of strength of the spring force of the thread tension spring. The rotating body is provided so as to be rotatable around the center of rotation, and has a conversion mechanism that moves the movable body along the spring force adjustment direction with the rotation. The rotating body has a cylindrical portion having a conversion mechanism and a plurality of internal teeth formed at a predetermined pitch circle diameter with respect to the rotation center on the inner peripheral wall of the cylindrical portion. The thread tension dial is provided so as to be rotatable with respect to the rotating body by a user's rotation operation, and is formed with a pitch circle diameter Dout smaller than the pitch circle diameter Din of the inner teeth of the rotating body and meshes with the inner teeth of the rotating body. It has several possible external teeth. When the user rotates the thread tension dial, the rotation speed of the thread tension dial is reduced by the engagement of the external teeth and the inner teeth, and the rotation body is transmitted to the rotating body to rotate in the same direction as the rotation of the thread tension dial. Let

(Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the sewing thread tension device 1 adjusts the thread tension, and is held by a bracket 240 (only a part of which is shown) attached to the sewing machine body 2. The sewing thread tension device 1 includes a first thread tension tray 31, a second thread tension tray 32 that faces the first thread tension tray 31 so that the yarn is sandwiched between the first thread tension tray 31, and the outer peripheral side of the shaft 40. , A thread tension spring 4 formed by a coil spring provided substantially coaxially, a movable body 5, a rotating body 6, and a thread tension dial 7.

  The first thread tension tray 31 is fixed to the sewing machine body 2. The second thread tension tray 32 is provided to face the first thread tension tray 31 so as to sandwich the yarn with the first thread tension tray 31. The thread tension spring 4 biases the second thread tension tray 32 in the direction of the arrow X1 toward the first thread tension tray 31 in a direction in which the second thread tension tray 32 approaches the first thread tension tray 31. This adjusts the yarn tension. Between the thread tension spring 4 and the movable body 5, a thread tension nut 8 having an uneven portion 80 for hooking on the outer peripheral portion is interposed. The spring force of the thread tension spring 4 that is an industrial product may vary at a minute level. Therefore, at the time of shipment or the like, the manufacturer can adjust the spring force of the thread tension spring 4 by rotating the thread tension nut 8 about its axis.

  The movable body 5 that functions as a thread tension plate is movable along a spring force adjustment direction (arrow X direction) that adjusts the degree of strength of the spring force of the thread tension spring 4. As shown in FIG. 1, the rotating body 6 is provided so as to be rotatable in the circumferential direction (in the directions of arrows A <b> 1 and A <b> 2) about an axis 60 m serving as the first rotation center 60. The rotating body 6 has a conversion mechanism 62 that moves the movable body 5 along the spring force adjustment direction (arrow X direction) as it rotates. When the rotating body 6 is rotated along the circumferential direction (arrow A1, A2 direction), the rotation of the rotating body 6 causes the conversion mechanism 62 to move the movable body 5 along the spring force adjustment direction (arrow X direction). Move. As a result, the degree of strength of the spring tension of the thread tension spring 4 is adjusted, the force for clamping the thread between the first thread tension tray 31 and the second thread tension tray 32 is adjusted, and consequently the thread tension of the upper thread is adjusted. .

  Further explanation will be added. As shown in FIG. 3, the conversion mechanism 62 includes a cam groove 63 formed in a spiral shape from one end 63 e to the other end 63 f with respect to the first rotation center 60 of the rotating body 6, and along the cam groove 63. The follower 65 is guided relatively. Since the follower 65 is provided integrally with the movable body 5, it can be displaced together with the movable body 5 in the direction of the arrow X, but does not rotate. As shown in FIG. 3, the cam groove 63 spirals with respect to the first rotation center 60 so that the distance L between the first rotation center 60 and the cam groove 63 gradually increases from the one end portion 63 e to the other end portion 63 f. It is formed in a shape. Here, as shown in FIG. 3, the distance L <b> 1 is a distance L <b> 1 between one end portion 63 e on the inner side of the cam groove 63 and the first rotation center 60. The distance L2 (L2> L1) between the other end portion 63f outside the diameter of the cam groove 63 and the rotation center is set. When the rotator 6 rotates around the first rotation center 60 in one direction (arrow A1 direction), the cam groove 63 rotates around the first rotation center 60 in the same direction as the rotator 6, and thus the follower. 65 is guided while being engaged with the cam groove 63 and moves in the direction of the arrow X1, whereby the movable body 5 moves in the direction of the arrow X1. As a result, the thread tension spring 4 is compressed in the direction of the arrow X1, the spring force of the thread tension spring 4 becomes stronger, the pressure contact force of the first thread tension tray 31 and the second thread tension tray 32 increases, and the thread of the upper thread The tension becomes stronger.

  On the other hand, as can be understood from FIG. 3, when the rotating body 6 rotates around the first rotation center 60 in the other direction (arrow A2 direction), the cam groove 63 together with the rotating body 6 Since the follower 65 rotates and rotates in the same direction, the follower 65 is guided while being engaged with the cam groove 63 and moved in the direction of the arrow X2, whereby the movable body 5 is moved in the direction of the arrow X2 by the spring force of the thread tension spring 4. To do. In this case, the thread tension spring 4 is extended in the direction of the arrow X2 by its own spring force. As a result, the spring tension of the thread tension spring 4 becomes weaker, and the pressure contact force between the first thread tension tray 31 and the second thread tension tray 32 Decreases, and the thread tension of the upper thread becomes weaker.

  According to this embodiment, as shown in FIG. 2, the rotating body 6 includes a cylindrical portion 66 having an outer peripheral surface 66 s and a plurality of internal teeth 67 arranged in parallel in the circumferential direction on the inner peripheral wall of the cylindrical portion 66. Have. As shown in FIG. 2, the inner teeth 67 are formed over the entire circumference in the inner circumferential portion of the cylindrical portion 66 so as to make one round around the first rotation center 60 of the rotating body 6. As shown in FIG. 2, the pitch circle diameter of the internal teeth 67 is indicated by Din. The pitch circle diameter Din of the inner teeth 67 is larger than the outer diameter DA of the thread tension dial 7 in consideration of the reduction ratio and the like. However, it is not limited to this.

  The thread tension dial 7 can be rotated around the second rotation center 70 of the shaft 70m by a user's rotation operation, and is held by a bracket 240 (see FIG. 1) of the sewing machine body 2 that holds the entire thread tension device 1. Has been. The thread tension dial 7 is provided coaxially with the outer cylinder 72 and an outer cylinder 72 having a concavo-convex part 71 extending in the circumferential direction (arrow B1, B2 direction) for frictional engagement of the fingertips. A gear 74 formed by the inner cylinder portion 73 and a shaft end surface 75 (see FIG. 1) connecting the inner cylinder portion 73 and the outer cylinder portion 72 are provided. As shown in FIG. 2, the gear 74 has a plurality of external teeth 77 that can mesh with the internal teeth 67 of the rotating body 6. The pitch circle diameter Dout of the outer teeth 77 of the gear 74 is made smaller than the pitch circle diameter Din of the inner teeth 67 of the rotating body 6 for reduction (Dout <Din).

  As can be understood from FIG. 2, when the thread tension dial 7 is rotated in the circumferential direction by the user, the rotating body reduces the rotational speed of the thread tension dial 7 due to the meshing of the outer teeth 77 and the inner teeth 67. 6 and the rotating body 6 is rotated in a direction common to the rotation direction of the thread tension dial 7. Accordingly, as can be understood from FIGS. 1 and 2, when the thread tension dial 7 is rotated in the direction of the arrow B1, the rotating body 6 has an arrow A1 that is common to the rotation direction of the thread tension dial 7 (the direction of the arrow B1). Rotate in the direction. When the thread tension dial 7 is rotated in the arrow B2 direction, the rotating body 6 rotates in the arrow A2 direction common to the rotation direction of the thread tension dial 7 (arrow B2 direction).

  That is, according to this embodiment, as can be understood from FIG. 2, when the user operates the thread tension dial 7 to rotate in the direction of the arrow B1 around the second rotation center 70, the external teeth 77 of the gear of the thread tension dial 7. Rotate in conjunction with each other, and the inner teeth 67 meshing with the outer teeth 77 rotate in the direction of the arrow A <b> 1 around the first rotation center 60 of the rotating body 6. As a result, the movable body 5 and the thread tension nut 8 move in the direction of the arrow X1, the thread tension spring 4 is displaced in the same direction, the second thread tension tray 32 approaches the first thread tension tray 31, and the upper thread yarn Adjust the tension slightly.

  Further, when the user operates the thread tension dial 7 to rotate in the direction of the arrow B2 around the second rotation center 70, the external teeth 77 of the gear of the thread tension dial 7 rotate in conjunction with each other, and the internal teeth that mesh with the external teeth 77. 67 rotates around the first rotation center 60 of the rotator 6 in the direction of arrow A2. As a result, the movable body 5 and the thread tension nut move in the arrow X2 direction, the thread tension spring 4 is displaced in the same direction, the second thread tension tray 32 is separated from the first thread tension tray 31, and the thread tension is weakened. Let them adjust.

  Here, as can be understood from FIG. 2, the pitch circle diameter Dout of the outer teeth 77 of the thread tension dial 7 is made smaller than the pitch circle diameter Din of the inner teeth 67 of the rotating body 6 (Dout <Din). Accordingly, the number Nout of the external teeth 77 is made smaller than the number Nin of the internal teeth 67 of the rotating body 6 (Nout <Nin). Therefore, when the thread tension dial 7 is rotated by the user, the outer teeth 77 of the thread tension dial 7 and the inner teeth 67 of the rotating body 6 mesh with each other, and the rotational speed of the thread tension dial 7 is reduced to the rotating body 6. A speed reduction mechanism 79 for transmission is formed. Therefore, when the user rotates the thread tension dial 7, the rotation of the thread tension dial 7 can be transmitted to the rotating body 6 while decelerating. Further, since the speed reduction mechanism is provided, it is possible to prevent the user from feeling that the rotation operation of the thread tension dial 7 is heavy.

  Here, according to the present embodiment, when the user directly rotates the rotating body 6, the rotating body 6 has a function of roughly adjusting the thread tension. If the user directly rotates the thread tension dial 7, the thread tension dial 7 has a function of finely adjusting the thread tension. Here, when adjusting the thread tension, since the rotation direction of the rotating body 6 and the rotation direction of the thread tension dial 7 are set in a common direction, the user temporarily confuses the rotating body 6 and the thread tension dial 7. Even if an erroneous operation is performed, there is only a difference between the rough adjustment and the fine adjustment of the thread tension, and there is no difference in the direction in which the strength of the thread tension is adjusted, so that operability is ensured.

  As described above, when the rotating body 6 is rotated, the rotation of the rotating body 6 causes the conversion mechanism 62 to move the movable body 5 along the spring force adjustment direction (arrow X1, X2 direction) along with the rotation. As a result, the strength of the spring force of the thread tension spring 4 is adjusted, the force for pinching the thread between the first thread tension tray 31 and the second thread tension tray 32 is adjusted, and the thread tension can be adjusted accordingly. According to this embodiment, the speed reduction mechanism 79 is formed when the outer teeth 77 of the thread tension dial 7 and the inner teeth 67 of the rotating body 6 mesh with each other. For this reason, the degree of strength of the spring force of the thread tension spring 4 can be finely adjusted, and the force for pinching the thread between the first thread tension tray 31 and the second thread tension tray 32 can be finely adjusted. Can be fine tuned. In this case, compared with the case where the speed reduction mechanism 79 is not provided, that is, compared with the case where the user directly rotates the rotating body 6, the rotating body 6 can be rotated with a small torque. In addition, the thread tension spring 4 can be moved with high accuracy, the degree of strength of the spring force of the thread tension spring 4 can be adjusted efficiently, and the thread tension can be finely adjusted.

  Further, as shown in FIG. 2, the outer diameter DA of the outer cylindrical portion 72 of the thread tension dial 7 is set larger than the pitch circle diameter Dout of the outer teeth 77 of the gear 74 of the thread tension dial 7. In this case, the rotation distance of the external teeth 77 of the gear 74 is smaller than the rotation distance by which the user rotates the outer cylinder portion 72 of the thread tension dial 7 in the circumferential direction. Also in this sense, a speed reduction mechanism for fine adjustment of the yarn tension can be formed.

  By the way, in order to obtain from a small thread tension to a large thread tension, it is preferable to use a highly rigid thread tension spring 4 having a high spring constant. Furthermore, when the thickness of the material to be sewn such as cloth is thick, it is preferable to increase the spring constant of the thread tension spring 4 to make the thread tension spring 4 hard in order to increase the thread tension. However, when the spring constant of the thread tension spring 4 is high, the rotational torque of the thread tension dial tends to become excessively large, and the user feels that the rotation operation of the thread tension dial 7 is heavy, causing a sense of discomfort. Further, even if the thread tension dial is rotated, the fluctuation of the strength of the spring tension of the thread tension spring 4 varies greatly and sensitively, and the degree of the strength of the spring tension of the thread tension spring 4 can be finely adjusted. Not always easy. As a result, it is not always easy to finely adjust the thread tension. Further, in order to make fine adjustment while increasing the spring constant of the thread tension spring 4, it is necessary to increase the stroke of the movable body 5 in the arrow X direction. However, the size of the movable body 5 in the arrow X direction increases. , There is a defect that damages the sewing machine design.

  In this regard, according to this embodiment, when the thread tension dial 7 is rotated by the user, when the outer teeth 77 of the thread tension dial 7 and the inner teeth 67 of the rotating body 6 mesh with each other, the rotation speed of the thread tension dial 7 is increased. Since the speed reducing mechanism 79 for reducing the speed of the thread tension spring 4 is formed, the torque for rotating the thread tension dial 7 by the user can be reduced even when the spring constant of the thread tension spring 4 is increased. It is possible to suppress the rotational operation of the thread tension dial 7 from being felt heavy, and it is possible to easily finely adjust the degree of strength of the spring tension of the thread tension spring 4. Therefore, it is possible to finely adjust the force for pinching the yarn between the first thread tension tray 31 and the second thread tension tray 32 and thereby finely adjust the thread tension.

  For this reason, according to this embodiment, even when the spring constant of the thread tension spring 4 is high, compared with the case where the speed reduction mechanism 79 is not provided, that is, when the user directly rotates the rotating body 6. As compared with the above, the degree of strength of the spring force of the thread tension spring 4 can be adjusted efficiently. Since there is no problem even when the spring constant of the thread tension spring 4 is high in this way, it is possible to reduce the size of the thread tension spring 4 in the axial direction and the like while increasing the spring constant of the thread tension spring 4. Of course, if the user wants to roughly adjust the thread tension, the user may rotate the rotating body 6 directly.

  According to the present embodiment, as shown in FIG. 1, the thread tension dial 7 has a shaft end surface 75 on the rotating body 6 side as a connecting portion that connects the outer cylinder portion 72 and the inner cylinder portion 73. As can be understood from FIG. 2, the thread tension dial 7 is provided such that the second rotation center 70 is eccentric to the upper side (arrow U direction side) with respect to the first rotation center 60 of the rotating body 6. The shaft end surface 75 of the outer cylinder portion 72 of the thread tension dial 7 has a concealing surface portion 75 a concealed by the rotating body 6 and an exposed surface portion 75 c exposed from the rotating body 6. As described above, the thread tension dial 7 and the rotating body 6 are arranged adjacent to each other, but the thread tension dial 7 is arranged eccentrically with respect to the first rotation center 60 of the rotating body 6. 7 and the rotating body 6 can be visually discriminated, and the trouble that they are confused and operated is suppressed. In particular, since the thread tension dial 7 is provided eccentrically on the upper side (arrow U direction side), the user can easily operate the thread tension dial 7.

  Further, according to the present embodiment, as shown in FIG. 1, the shaft end surface 68 of the rotating body 6 is exposed to the outside, and the display unit 69 indicating the degree of strength for coarse adjustment of the thread tension of the upper thread is provided. I have. The display unit 69 allows the user to recognize the degree of strength for coarse adjustment of the yarn tension. In addition, the direction of the display unit 69 indicating the degree of yarn tension strength and the rotating operation direction of the rotating body 6 are common. In other words, when the rotating body 6 is rotated in the direction of the arrow A1 in order to increase the thread tension, the display unit 69 indicates the degree of thread tension. For this reason, the user can rotate the rotating body 6 for coarse tension adjustment without feeling uncomfortable.

  In addition, according to the present embodiment, as shown in FIG. 1, the shaft end surface 75 of the thread tension dial 7 is provided with a display portion 78 that indicates the degree of strength for fine adjustment of the thread tension of the upper thread. The user can visually recognize the display section 78 for fine adjustment of the exposed surface portion 75c. That is, with the rotation operation of the thread tension dial 7 by the user, the shaft end surface 75 of the thread tension dial 7 is switched from the concealment surface portion 75 a concealed by the rotator 6 to the exposed surface portion 75 c exposed from the rotator 6. be able to. For this reason, the user can easily recognize the degree of strength for fine adjustment of the thread tension by the display unit 78 indicating the degree of strength for fine adjustment of the thread tension formed on the shaft end surface 75 of the thread tension dial 7. In addition, the rotation operation direction of the display unit 78 indicating the degree of the yarn tension strength and the rotation operation direction of the thread tension dial 7 are common. That is, when the thread tension dial 7 is rotated in the direction of the arrow B1 in order to increase the thread tension, the display unit 78 indicates a high degree of thread tension. For this reason, the user can operate the thread tension dial 7 for fine tension adjustment without feeling uncomfortable. Even if the user confused and operated the rotation operation of the thread tension dial 7 and the rotation operation of the rotating body 6, the display units 69 and 78 indicate the direction of the thread tension and the thread tension. Since the rotation direction of the dial 7 and the rotating body 6 is common, a large adverse effect due to confusion is suppressed.

  According to the present embodiment, as can be understood from FIG. 1, the shaft end surface 68 of the rotating body 6 and the shaft end surface 75 of the thread tension dial 7 are exposed in the same direction and are visually recognized by the user. Accordingly, the display unit 69 for displaying the rough thread tension formed on the shaft end surface 68 and the display unit 78 for displaying the fine thread tension formed on the shaft end surface 75 are exposed in the same direction, and are thus displayed by the user. It is easily visible.

(Application form)
FIG. 4 shows an application form. The sewing machine body 2 of the sewing machine includes a bed portion 22, a vertical arm portion 23 extending upward from one end portion of the bed portion 22, a horizontal arm portion 24 extending horizontally from an upper portion of the vertical arm portion 23, and a needle bar for attaching a needle. 25 and a press-up lever 26 for operating the presser bar up and down. The bracket 240 of the lateral arm portion 24 is provided with a thread tension device 1 that is operated by a user to adjust the tension of the upper thread.

(Other)
According to the above-described embodiment, the conversion mechanism 62 that converts the rotational motion of the rotating body 6 into the linear motion of the movable body 5 uses the cam groove 63, but is not limited to this, and other cams such as a cylindrical cam. In short, it is only necessary that the rotational motion of the rotating body 6 can be changed to the linear motion of the movable body 5. The thread tension dial 7 is eccentrically provided on the upper side (arrow U direction side), but may protrude to the user side facing the front of the sewing machine. The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope not departing from the gist.

1 is a sewing thread tension device, 2 is a sewing machine body, 240 is a bracket, 31 is a first thread tension tray, 32 is a second thread tension tray, 4 is a thread tension spring, 5 is a movable body, 6 is a rotating body, and 60 is 1st rotation center, 62 is a conversion mechanism, 63 is a cam groove, 65 is a follower, 67 is an internal tooth, 68 is a shaft end face, 69 is a display part, 7 is a thread tension dial, 70 is a 2nd rotation center, 8 is A thread tension nut, 75 is a shaft end surface, 75a is a concealing surface portion, 75c is an exposed surface portion, 77 is an external tooth, 78 is a display portion, and 79 is a speed reduction mechanism.

Claims (5)

A sewing thread tension device that is provided in the sewing machine and adjusts the thread tension,
A first thread tension plate,
A second thread tension tray facing the first thread tension tray so as to sandwich the yarn with the first thread tension tray;
A thread tension having a spring force that adjusts the thread tension by urging the second thread tension tray toward the first thread tension tray in a direction in which the first thread tension tray and the second thread tension tray approach each other. Spring,
A movable body movable along a spring force adjustment direction for adjusting the degree of strength of the spring force of the thread tension spring;
A cylindrical portion, a conversion mechanism that moves the movable body along the direction of the spring force adjustment along with the rotation, and a predetermined center with respect to the rotation center on the inner peripheral wall of the cylindrical portion. A rotating body having a plurality of internal teeth formed with a pitch circle diameter;
It is provided so as to be rotatable with respect to the rotating body by a user's rotation operation, is formed with a pitch circle diameter Dout smaller than the pitch circle diameter Din of the inner teeth of the rotating body, and can mesh with the inner teeth of the rotating body. A thread tension dial that has a plurality of external teeth and transmits the rotation so as to reduce the rotation speed of the rotating body by meshing the external teeth and the internal teeth with the rotation, thereby rotating the rotating body in a common direction. A sewing thread tension device characterized by comprising:   2. The thread tension dial according to claim 1, wherein the thread tension dial includes an outer cylinder part that is rotated by a user, and a gear that is formed coaxially with respect to the outer cylinder part and formed with an inner cylinder part having the external teeth. Sewing thread tension device characterized by The shaft end face as a connecting portion according to claim 2, wherein the thread tension dial is provided so that a rotation center thereof is eccentric with respect to a rotation center of the rotating body, and connects the outer cylinder portion and the inner cylinder portion. On the rotating body side,
The shaft end surface includes a concealing surface portion concealed by the rotating body and an exposed surface portion exposed from the rotating body.   4. The shaft end surface of the thread tension dial according to claim 3, further comprising a display unit that indicates a degree of thread tension strength, a direction of the display unit that indicates a degree of thread tension strength, and a direction of the thread tension dial. A sewing thread tension device characterized by having a common rotation direction. A sewing machine comprising a sewing thread tension device for adjusting the thread tension,
The sewing thread tension device is
A first thread tension plate,
A second thread tension tray facing the first thread tension tray so as to sandwich the yarn with the first thread tension tray;
A thread tension having a spring force that adjusts the thread tension by urging the second thread tension tray toward the first thread tension tray in a direction in which the first thread tension tray and the second thread tension tray approach each other. Spring,
A movable body movable along a spring force adjustment direction for adjusting the degree of strength of the spring force of the thread tension spring;
A cylindrical portion, a conversion mechanism that moves the movable body along the direction of the spring force adjustment along with the rotation, and a predetermined center with respect to the rotation center on the inner peripheral wall of the cylindrical portion. A rotating body having a plurality of internal teeth formed with a pitch circle diameter;
It is provided so as to be rotatable with respect to the rotating body by a user's rotation operation, is formed with a pitch circle diameter Dout smaller than the pitch circle diameter Din of the inner teeth of the rotating body, and can mesh with the inner teeth of the rotating body. A thread tension dial that has a plurality of external teeth and transmits the rotation so as to reduce the rotation speed of the rotating body by meshing the external teeth and the internal teeth with the rotation, thereby rotating the rotating body in a common direction. A sewing machine characterized by comprising:

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