JPS63283683A - Sewing machine having belt tension control apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a sewing machine having a structure including a needle bar for operating an upper thread and a hook for operating a lower thread. More specifically, the present invention relates to a sewing machine having a main shaft for operating a needle bar, a hook shaft for operating a hook, and an endless belt interposed between the main shaft and the hook shaft, in which the tension of the endless belt is adjusted.

INDUSTRIAL APPLICATION This invention can be utilized for a small household cycle sewing machine.

(Prior Art) Conventionally, in sewing machines that have a needle bar that operates the upper thread and a hook that operates the bobbin thread, a main shaft that operates the needle bar and a hook shaft that operates the hook are disposed in the housing. Furthermore, an endless belt is disposed between the main shaft and the hook shaft. and,
The rotational driving force of the main shaft that operates the needle bar is transmitted to the shuttle shaft via an endless belt, causing the shuttle to rotate.

(Problems to be Solved by the Invention) Conventionally, sewing machines have been provided that are equipped with a belt tension adjustment device in order to prevent the endless belt from loosening and ensure synchronization between the needle bar and the hook. The belt tension adjustment device is formed by a bracket having a tension control roller and an elongated hole extending in the direction of the tension roller, and a tightening screw member held on the wall of the housing through the elongated hole. The position of the elongated hole tightened by the tightening screw member is adjusted to adjust the pressing force of the tension roller that biases the endless belt. In this belt tension adjustment device, the tension roller can be displaced by the size of the elongated hole in the bracket. Note that after adjusting the position of the tension roller, the tightening screw member is tightened at that position to fix the relative position of the bracket and thus the tension roller.

The present invention has been developed to meet the above-mentioned circumstances, and further provides a sewing machine equipped with a belt tension adjustment device that allows easy adjustment of an endless belt. To provide a sewing machine with an adjustment device.

[Structure of the Invention] (Means for Solving Problems) A sewing machine according to the present invention includes a housing, a needle bar arm that is built in the housing and that operates an upper thread, a hook that operates a bobbin thread, and a hook that operates the needle bar arm. It consists of a main shaft to operate, a hook shaft to operate the hook, and an actuating section having an endless belt connecting the main shaft and the hook shaft.The operating section has a first pulley attached to the main shaft side and a hook shaft to the hook shaft side. The outer periphery of the attached second pulley and first pulley and the second
It has an endless belt stretched around the outer periphery of the pulley and a belt tension adjustment device that adjusts the tension of the endless belt, and the belt tension adjustment device includes a tension roller and a holding part that rotatably holds the tension roller at one end. and a deformable part provided between one end and the fixed part, the other end of which is a fixed part fixed to the housing, and a deformation adjustment part that moves the holding part relative to the housing. This is a characteristic feature.

The operating section is a mechanism built into the housing for sewing by threading the upper thread and bobbin thread, and includes a needle bar arm that operates the upper thread, a hook, a main shaft that operates the needle bar arm, and the hook. It has a hook shaft that operates. In order to hold the needle bar arm, it is preferable that a swing ring is horizontally disposed in the housing and that the needle bar arm is pivotally supported on the swing shaft. It is desirable that the axis of the rocking ring and the upper surface of the needle plate held in the housing and having the needle insertion hole are set at approximately the same height. If the heights are approximately the same in this way, when the needle fixed at the tip of the needle bar arm oscillates, the inner center of the oscillating needle, the upper surface of the needle plate, and the axis of the oscillating shaft will be aligned. The connecting lines substantially coincide, which is therefore advantageous for vertically inserting the needle into the fabric held on the upper surface of the throat plate.

Considering that the needle is inserted perpendicularly into the cloth, it is desirable that the swing axis, which is the center of swing of the needle bar arm, be located far from the needle at the tip of the needle bar arm. It is preferable that the needle bar arm is formed of a low rising portion pivotally supported on a swing shaft and a horizontally long arm portion pivotally supported on the rising portion. In this case, since the needle is attached to the tip of the horizontally long arm, it is possible to increase the length of the horizontally long arm and the distance between the surface of the needle and the swinging ring, and to increase the radius of curvature when the needle swings. This is advantageous, and because the height of the riser is low, it is advantageous to reduce the height of the housing. Note that when using a curved needle, the axis of the pivot shaft and the top of the needle plate may not necessarily be at the same height, but it is possible to insert the needle vertically into the fabric. Be filial.

Considering the transmission of driving force to the hook shaft, the reduction of the height of the housing, etc., it is desirable that the hook shaft and the main shaft are disposed horizontally and parallel to each other.

The operating part includes a first pulley attached to the main shaft side, a second pulley attached to the hook shaft side, and an endless belt stretched around the outer circumference of the first pulley and the outer circumference of the second pulley. and,
It has a belt tension adjustment device that adjusts the tension of the endless belt. The first pulley and the second pulley can be timing gears, and the endless belt is preferably a timing belt. This is advantageous in improving the synchronization between the needle bar arm on the side that operates the upper thread and the hook on the side that operates the lower thread.

The belt tension adjustment device includes a tension roller that presses an endless belt, a holding section that rotatably holds the tension roller at one end, and a fixed section that is fixed to a housing at the other end, which is provided between the one end and the fixed section. and a deformation adjustment part that moves the holding part relative to the housing. As a means for fixing the fixed part to the housing, known means such as screws can be used. When a slit is formed in the deformable portion, the deformable portion becomes easier to deform. The deformation adjustment section has a function of moving the holding section of the bracket, such as a screw member, relative to the housing.

A top pin is usually arranged adjacent to the needle bar arm.

The take-up is operated by the main shaft. As shown in the embodiment described above, the take-up has a low-height rising arm that is connected to the main shaft and swings as the main shaft rotates, and an upper arm that is pivotally supported by the rising arm and moves almost horizontally. The thread hook can be formed by an oblong arm with a hook for use. In this way, the hook of the top pin reciprocates in a substantially horizontal direction, which is advantageous in reducing the height of the housing.

(Operation) Thread the upper thread through the needle and rotate the main shaft with the fabric set below the needle. When the main shaft rotates, the needle bar arm operates and the upper thread is operated. At the same time, the rotation of the main shaft is transmitted to the hook shaft via the first pulley, the endless belt, and the second pulley, the hook rotates, and the bobbin thread is operated. A seam is thus formed in the cloth.

By the way, when the endless belt becomes loose, the belt tension adjustment device is operated to deform the elastic deformation portion of the bracket and move the holding portion relative to the housing. This adjusts the tension of the endless belt.

(Example) Hereinafter, an example of a sewing machine according to the present invention will be described with reference to the drawings.

The sewing machine according to this embodiment is applied to a small cycle sewing machine for home use that performs embroidery. Each component will be explained below with reference to the drawings. Figure 1 is an external perspective view of the entire sewing machine, Figure 2 is an exploded perspective view of the main parts of the sewing machine, Figure 3 is a bottom view of the sewing machine with the bed cover removed, and Figure 4 is the mV- A cross-sectional view along the TV line, Figure 5 is v in Figure 3.
Figure 6 is a sectional view taken along the line vt-■ in Figure 3, Figure 7 is a plan view with the top cover removed, and Figure 8 is a cross-sectional view taken along the line ■-■ in Figure 3. A cross-sectional view of the tightened surface.

(composition) The housing 1 will be explained mainly with reference to FIG.

As shown in FIG. 1, the housing 1 includes a bed housing 10 that forms a lower part and is thinned in the height direction, and an arm housing 11 that rises upward from the end of the bed housing 10 and extends laterally. , 1ml in the upper opening of the arm housing 11! It consists of a top cover 12 that is freely attached. An embroidery frame section 13 is attached to the bed housing 10. The embroidery frame portion 13 is an outer frame 130
and an inner frame 131. The cloth to be embroidered is sandwiched between the outer frame 130 and the inner frame 131 by operating the operating tool 130a. The embroidery frame section 13 is attached to a moving section 132 and can be moved in the X and Y directions by an X-direction motor and a Y-direction motor including a stepping motor built into the motor section 100 of the housing 1 . The X-direction motor and the Y-direction motor are driven by a part whose main component is a CPU built into the housing 1, and move the embroidery frame 13 to appropriate positions in the X-direction and Y-direction. . Note that an embroidery program is stored in the memory element of the w4II1 section, and the X-direction motor and the Y-direction motor are driven according to this program to move the embroidery frame section 13. A needle plate 14 is attached to the upper surface of the bed housing 10 of the housing 1 and is located below the tip of the arm housing 11 and has a τ needle insertion hole 140. Note that the Y motor is illustrated as a Y motor 16 in FIG.

The needle bar arm 2 will be explained mainly with reference to FIGS. 2, 4, and 5. The needle bar arm 2 is formed of a laterally elongated arm portion 20 that extends obliquely laterally and becomes narrower toward the tip, and a wider rising portion 21 that is integral with the laterally elongated arm portion 20 and has a lower height. The needle bar 2 is inserted into the hole 20b at the tip of the needle bar arm 2.
2 is attached with a set screw 223. Needle bar 22
A needle clamp 23 is attached to the lower end of the sewing machine with a needle clamp screw 230, and a sewing needle 24 is attached to the needle clamp 23. The height of the rising portion 21 of the needle bar arm 2 is set so that the needle 24 swinging about the swing shaft 30 is perpendicular to the needle plate 14 or nearly vertical. It is set in consideration of the height of the needle 24, etc. A presser bar 25 is inserted into a hole 20a at the tip of the horizontally long arm portion 20 of the needle bar arm 2 so as to be able to protrude freely. The upper end of the presser bar 25 has a retaining ring 25
Removal is prevented with a 010 ring 251. Presser bar 25
A metal presser foot main body 26 having a cloth presser function is attached to the lower end of the presser foot body 26. . A guide rod 27 attached to the presser foot body 26 is inserted into a guide hole 28 of the needle bar arm 2, as shown in FIG. A spring 29 is interposed between the presser foot body 26 and the needle bar l812. Presser foot body 26
An elastic body 32 made of ring-shaped rubber is attached to the lower surface of the holder to enhance the buffer function and the presser function.

A swing shaft 30 is inserted through a hole 21a formed in the lower part of the rising portion 21 of the needle bar arm 2 so as to be oriented in the horizontal direction. The swing shaft 30 has a bearing 300 and a spring 3 shown in FIG.
01, it is pivoted in the horizontal direction via a retaining ring 302 on the wall 10a near the recess 10b formed in the bed 101 of the bed housing 10 of the housing 1, as shown in FIG.

The operating portion for swinging the needle bar arm 2 is a support 1 formed inside the bed housing 1o of the housing 1 shown in FIG.
Motor mounting plate 400 tightened with screw 400a at 0h
a drive motor 40 held in the drive motor 40; a large-diameter intermediate pulley 41 for deceleration; a belt 48 stretched between the intermediate pulley 41 and the pulley 40a press-fitted onto the motor shaft of the drive motor 40; 41 gear 41a, a main shaft 43 that rotates together with the large gear 42 as shown in FIG. 2, and a take-up crank 44 fixed to the end of the main shaft 43 with a pin 440. and a hole 45a that fits into the cam portion 44a of the top crank 44 as shown in FIG.
It has a needle bar crank 0 and 45. As shown in FIG. 5, a spherical bearing 43a is inserted through the main shaft 43. As shown in FIG. 3, the spherical bearing 43a is attached to the bed housing 10 through a holder 10h which is tightened by a screw 109 in the portion 10e1.

As shown in FIG. 3, the intermediate pulley 41 is supported by a support shaft 49. The spindle 49 has a retaining ring 49a on the plate 400 to attach the motor.
It is installed through.

As shown in FIG. 2, the hole 45c in the connecting rod portion 45b of the needle bar crank rod 45 and the hole 2 in the rising portion 21 of the needle bar arm 2
1b, a shaft 46 is held via a retaining ring 46a. Here, as is clear from Fig. 5, crank 4
The cam portion 44a of No. 4 is eccentric with respect to the axis of the main shaft 43. Therefore, when the main shaft 43 rotates, the eccentric cam portion 44a rotates, so that the connecting rod portion 45b of the needle bar crank rod 45 reciprocates in the vertical direction.

As a result, the rising portion 21 of the needle bar arm 2 reciprocates in the vertical direction, so that the needle bar arm 2 moves to the fourth position about the pivot shaft 30.
It reciprocates in the six arrow directions shown in the figure and in the A' force direction.

As shown in FIG. 2, a thread take-up 6 is provided beside the needle bar arm 2 to loosen or tension the needle thread. The top pin 6 is formed by a rising arm 60 with a low height and a horizontally long arm 61 pivotally supported by a pin 60a. Top pin 6
operates with a so-called slider link mechanism. That is, a slide shaft 62 is attached to a hole 6a formed at the lower end of the rising arm 60 of the top pin 6. Slide shaft 62
A powder alloy bushing 64 that functions as a slider is slidably inserted into the bushing holder 6 on both sides of the slide shaft 62 in the axial direction.
It is held between 5.

As shown in FIG. 4, a pivot hole 60a formed near the hole 6a of the rising arm 60 of the C-bin 6 has a bearing 60b.
A take-up shaft 63 is inserted through the hole. The take-up pin 6 is pivotally supported to swing around a take-up pin shaft 63. Here, as shown in FIG. 2, a crank pin 47 having a U-shaped portion 470 at its tip is rotatably fitted into the hole 44b of the top crank 44. As shown in FIG. 4, the U-shaped portion 470 holds the bushing 64. An upward hook 66 is provided at the tip of the oblong arm 61 of the take-up bin 6, and two hooks are provided on both sides of the hook 66.
engagement grooves 67 are provided. As shown in FIG. 4, a guide member 1 has a guide elongated hole 150 formed directly below the top plate 110 of the arm housing 11 of the housing 1.
5 are arranged horizontally. The peripheral edge 151 forming the guide elongated hole 150 and each engagement groove 67 of the seven hooks 66 engage with each other,
The engagement groove 67 of the hook 66 is guided in a substantially horizontal direction along the guide elongated hole 150. At this time, since the peripheral portions 151 forming the guide elongated holes 150 are located on both sides of the hook 66, it is advantageous to prevent the hook 66 from falling down. Note that the tip of the hook 66 protrudes above the top plate 110 of the arm housing 11.

As shown in FIGS. 4 and 6, a hook 7 is disposed within the bed housing 10 of the housing 1 below the throat plate 14. As shown in FIGS. The hook 7 is fixed to a hook shaft 79 with a set screw 792, and the hook shaft 79 is disposed in the bed housing 10 of the housing 1 in a horizontal direction and parallel to the main shaft 43 via a spherical bearing 790. As shown in FIG.
It is held via a holder 10L which is tightened by a screw holder 10L. In addition, in FIG. 4, 7a is a hook retainer fixed with screws 7b.

As shown in FIG. 6, a small timing gear 78 as a second pulley is attached to the hook shaft 79 via a set screw 780. On the other hand, as shown in FIGS. 2 and 5, a clutch operating ring 70, a one-way clutch 71 made of a plate spring, a ring 72, and a large timing gear 73 as a first pulley are attached to the main shaft 43. The large timing gear 73 is connected to the main shaft 43 via a shaft portion 731 and a set screw 73a, and operates in conjunction with the main shaft 43.

A toothed timing belt 77 as an endless belt is stretched between the large timing gear 73 and the small timing gear 78.

A protrusion 710 of the one-way clutch 71 is engaged with a slit 700 of the clutch actuation ring 70. A protruding piece 711 of the one-way clutch 71 is engaged with a slit 730 of the large timing gear 73.

As shown in FIGS. 2 and 8, the clutch actuating ring 7
0, a solenoid 74 and a clutch actuating pawl 75 are adjacent to each other. The support shaft 49 is inserted through the hole 75a of the clutch actuating pawl 75, and the clutch actuating pawl 75 swings around the hole 75a. The pin 75b of the clutch actuation pawl 75 is the solenoid 7
It is fitted into the hole 741 of the α-piece 740 of No. 4 via a retaining ring 742. The clutch actuating pawl 75 is a spring 76
The clutch actuating pawl 75 is biased by the biasing force.
rotates around the hole 75a, and the pawl 751 attempts to press the pawl 701 of the clutch actuating ring 70, but since it is being sucked by the solenoid 74 via the rod 740, the pawl 701 of the clutch actuating ring 70 is not engaged. has been solved. Therefore, the one-way clutch 71 operates in the tightening direction, and the main shaft 43 and the large timing gear 73 are connected via the one-way clutch 71 that is tightened. Therefore, when the large gear 42 rotates and the main shaft 43 rotates, the large timing gear 73 rotates in conjunction. Then, the toothed timing belt 77 rotates, and the small timing gear 76
rotates, the hook shaft 77 and hook 7 rotate, and the bobbin thread is operated.

In this embodiment, the number of teeth of the large timing gear 73 is set to twice the number of teeth of the small timing gear 78. Therefore, when the large timing gear 73 rotates once, the small timing gear 78 rotates twice. That is, when the main shaft 43 rotates once and the needle bar arm 2 reciprocates once, the hook 7 rotates twice. Note that the end 76a of the spring 76 is locked in a locking hole 823 of a bracket 80, which will be described later.

When it is desired to stop the rotation of the hook 70 to finish sewing, etc., the control section described above operates the solenoid 74. Therefore O
As the bolt 740 moves forward, the clutch actuating pawl 75 rotates around the hole 75a, and the pawl 751 and the pawl 701 of the clutch actuating ring 70 are engaged. Therefore, one-way clutch 7
1 operates in the opening direction, and even though the large gear 42 rotates, the main shaft 43 and the large timing gear 73 do not rotate. Therefore, the large timing gear 73 is stopped, the timing belt 77 is not operated, and the rotation of M7 is stopped. In addition, solenoid 74
As shown in FIG. 8, the motor mounted on the support column 10h formed on the bed housing 10 is attached to the plate 400 through screws 743 within the bed housing 10.

As shown in FIGS. 2 and 8, the timing belt 77
A belt tension adjustment device al18 having a bracket 80 and an adjustment screw 84 is disposed above the belt tension adjustment device al18. The bracket 80 is formed of a metal plate, and includes a fixing part 81 having a fixing hole 810 and a tension roller 820 attached to the pulley shaft 8 at one end.
The holding part 82 is rotatably supported by a shaft 24, and a deformable part 83 is located between the holding part 82 and the fixed part 81.

Note that the fixed portion 81 and the deformable portion 83 are separated and partitioned by a slit 830. The holding portion 82 is formed into a U-shaped cross section with two side walls 82a and a ceiling wall 82b connecting each side wall 82a so as to have a reinforcing rib effect to ensure rigidity. - The holding portion 82 becomes wider toward the fixed portion 81. Further, the holding portion 82 includes a protruding piece 82.
1 is extended, and the protruding piece 821 has a screw hole 82 with a female thread.
2 is formed. Bracket 8 as shown in FIG.
0 is fixed to the lower surface of the bed 101 of the bed housing 10 of the housing 1 by inserting a set screw 810a into a fixing hole 810. Here, an adjustment screw 84 functioning as a deformation adjustment section having a male thread is connected to a screw hole 822 of the projection piece 821.
is screwed into. When the adjustment screw 84 is turned, the tip thereof comes into contact with the contact portion 10C provided on the lower surface of the bed 101 of the bed housing 10. 1.11 node screw 8 after contact
4 and turn it further, through the deformation of the deformation part 83,
In other words, the deformed portion 83 serves as a hinge, and the adjustment screw 84
The protruding piece 821 having the screw hole 822 screwed into it is displaced in the vertical direction and tends to separate from the bed 101 of the bed housing 10. Therefore, the tension control roller 820 pushes the timing belt 77, and the timing belt 77 becomes tense. Therefore, loosening of the timing bolt 77 can be prevented, the rotation of the large timing gear 73 can be reliably transmitted to the small timing gear 78, and the synchronization between the hook 7 and the needle bar arm 2 can be improved.
In other words, this is advantageous in ensuring synchronicity between the upper thread and the lower thread.

In addition, as shown in FIG. 2 and FIG. 5, the main shaft 43 includes:
A detection plate 85 consisting of a large circle and a small circle is attached, and further,
A handwheel 86, which is manually operated by a user, is attached by a set screw 861. The rotation of the detection plate 85, that is, the rotation of the main shaft 43, is detected by a photointerrupter 850.

A photointerrupter 850 is built into the bed 10 and functions as a visual sensor. Note that when the handwheel 86 is in a stopped state and the drive motor 40 is stopped, the handwheel 86
is manually turned by an operator to rotate the main shaft 43, thereby correcting the positions of the hook 7, needle bar arm 2, and take-up pin 6. As shown in FIG. 3, the spherical bearing 860 is attached to the bed housing 10 by being held in the holder 10h which is fastened to the portion 10d with a screw 10f.

(Operation) Now, the operation of the sewing machine according to the above embodiment will be explained.

First, the cloth is set in the embroidery frame 13, and the needle 24 is
With the upper thread hooked onto the hook 66 of the thread take-up 6, the operation switch is operated to cause the drive motor 40 to rotate. Therefore, the rotation of the drive motor 40 causes the belt 48, intermediate pulley 41, large gear 42, and main shaft 43 to rotate counterclockwise in FIG. 2. Then, as mentioned above, the main shaft 4
The cam portion 4 of the top crank 44 is eccentric with respect to 3.
4a rotates, the connecting rod portion 45b of the needle bar crank rod 45, which is fitted into the cam portion 44a, swings in the vertical direction. Therefore, the shaft 46 is attached to the rod portion 45b.
The rising portion 21 of the needle bar arm 2 connected to the needle bar arm 2 moves in the vertical direction, and as a result, the needle bar arm 2 moves in the direction of the arrow shown in FIG. oscillate. Therefore, the needle 24 is inserted into the needle insertion hole 140 of the needle plate 14 and removed from the needle insertion hole 140. In this case, the horizontally long arm portion 2o of the needle bar arm 2 is long in the horizontal direction, and the swing shaft 30 is located far from the needle 24, so that the radius of curvature around which the needle 24 swings becomes large, and the axis of the swing shaft 30 is Throat plate 14
Since the needle 24 is set at approximately the same height as the upper surface of the needle 24, the needle 24 that has swung in the direction of the arrow is perpendicular or nearly perpendicular to the throat plate 14 in the vicinity of the throat plate 14. Therefore, the needle 24 is inserted into the cloth held in the embroidery frame 13 and into the needle insertion hole 140 in a vertical or nearly vertical state. FIG. 9 shows a state where the needle bar arm 2 is at the top dead center when it is fully raised, and FIG. 11 shows a state where the needle bar arm 2 is at the bottom dead center when it is fully lowered. As the main shaft 43 rotates, the needle bar arm 2 moves as shown in FIGS.
It swings in the order of FIG. 11 and FIG. 12.

In this embodiment, when the main shaft 43 rotates, the large timing gear 73 rotates via the one-way clutch 71, the timing belt 77 rotates, and the small timing gear 78 rotates. Therefore, the rotation of the small timing gear 78 rotates the hook shaft 79, and the hook 7 rotates in synchronization with the swinging of the needle bar arm 2. In other words, when the needle bar arm 2 reciprocates once, the hook 7 rotates twice, and the needle 24 rotates. When the needle 2 passes through the needle insertion hole 140 through the cloth held in the embroidery frame 13 above the needle plate 14, the needle 2
The bobbin thread from hook 7 gets caught on the upper thread hooked to hook 4,
A stitch is formed on the fabric of the embroidery frame 13 by the upper thread and the lower thread. In this case, the embroidery frame section 13 is moved by the X-direction motor and the Y-direction motor controlled by the above-mentioned control section, thereby forming embroidery on the cloth.

By the way, when the timing belt 77 becomes loose, by turning the adjustment screw 84, the tip of the adjustment screw 84 can be adjusted to the bed housing 10.
It comes into contact with a contact portion 10c provided on the lower surface of the upper surface portion 101. When the adjustment screw 84 is turned further in the state of contact, the elastic deformation portion 83 acts as a hinge, and the screw threadedly engaged with the adjustment screw 84 deforms through the deformation of the elastic deformation portion 83. The protruding piece 821 having the hole 822 is displaced in the vertical direction,
It tries to move away from the upper surface part 101 of the bet 10.

Therefore, the tensidine roller 820 is connected to the timing belt 7.
Pressing 7, Timing Helt 77 gets nervous. Therefore, the rotation of the large timing gear 73 can be reliably transmitted to the small timing gear 78.

Next, the operation of the take-up 6 will be explained. When the main shaft 43 rotates counterclockwise, the column 47 of the take-up crank 44
The bushing 64 held at zero rotates about the axis of the main shaft 43 counterclockwise, that is, in the direction of arrow C in FIG. At this time, the crank pin 47 rotates relative to the hole 44b of the top crank 44, so the U-shaped portion 470#
and bushing 64 change direction. When the bushing 64 rotates in the direction of arrow C as described above, the U-shaped portion 470
While sliding on the slide shaft 62, the bushing 64 held in the slide shaft 62 repeatedly slides back and forth in the length direction of the slide shaft 62. At this time, as shown in FIG. 4, the base end 62b of the slide shaft 62 is restricted by the hole 6a, so as the bushing 64 rotates in the direction of arrow C,
As shown in FIG. 2, the inclination angle of the slide shaft 62 varies.

As the inclination angle of the slide shaft 62 changes as described above, the rising arm 6 of the take-up 6 to which the slide shaft 62 is fixed
0 swings back and forth in the direction of the arrow and in the direction of the arrow D'.

On the other hand, the engagement groove 67 of the hook 66 is guided by the guide elongated hole 150 of the guide member 15 and reciprocates in the horizontal direction, so the horizontally long arm 61 of the take-up lever 6 moves in the horizontal direction, that is, in the direction of the arrow E and the direction of the arrow E. - Move back and forth in the force direction.

From the state shown by the solid line in FIG. 9, where the needle bar arm 2 is at the top dead center,
When the bushing 64 rotates in the direction of the arrow C about the axis 43b of the main shaft 43, the slide shaft 62 whose inclination angle is regulated by the bushing 64 and the hole 6a rises slightly as shown by the two-dot chain line in FIG. climb. Therefore, the rising arm 6
0 begins to swing in one direction indicated by the arrow in FIG. Therefore, the hook 66 of the take-up bin 6 moves in the direction of arrow E and approaches the top dead center. FIG. 10 shows the state in which the take-up lever 6 is at the top dead center position.

Furthermore, from the top dead center position of the top pin 6 shown in FIG.
The take-up crank 44 rotates and the bushing 64 moves to the 10th position.
When further rotated in the direction of arrow C shown in the figure, two points ta! are shown in Figure 10! i! As shown in , the slide shaft 62 whose inclination angle is regulated by the bushing 64 and the hole 6a is tilted in a slightly more reclined direction than before.

As a result, the rising arm 60 of the take-up lever 6 begins to swing in the direction of the arrow, and the hook 66 begins to move in the direction of the arrow E shown in FIG. Therefore, the tension on the upper thread that has been hung on the hook 66 is relaxed.

Here, FIG. 10 shows the state just before the needle 24 is inserted into the fabric. Immediately before the needle 24 is inserted into the fabric, the upper thread is cut in order to prevent the upper thread from being cut due to tension. We need to loosen the tension. Therefore, as described above, the hook 66 moves in the direction of the arrow E to loosen the upper thread hooked on the hook 66.

In FIG. 11, a state in which the bushing 64 is further rotated in the direction of arrow C is shown by a solid line. In FIG. 11, the hook 66 has moved further toward the needle 24 than in the case of FIG. 10, loosening the upper thread. When the take-up crank 44 further rotates and the bushing 64 rotates in the direction of arrow C shown in FIG. 11 from the state shown by the solid line in FIG. Approach the direction of sleep in a nearly horizontal position. Therefore, the rising arm 60 of the top pin 6
advances the rocking in the direction of the arrow shown in FIG. Therefore, the hook 66 of the take-up pin 6 moves further toward the needle 24 and approaches the bottom dead center of the take-up pin. FIG. 12 shows the state of the top pin 6 at the bottom dead center when it has fully advanced.

By the way, the above-mentioned take-up 6 has a quick return mechanism. That is, from the state of the top dead center of the take-up pin shown by the solid line in Fig. 10, through the state shown by the solid line and the two-dot chain line in Fig. 11, until the state of the take-up pin bottom dead center shown by the solid line in Fig. 12. 12, when the hook 66 is directed toward the needle 24 side, the bushing 64 is attached to the main shaft 430, as shown in FIG.
It must be rotated by an angle θ1. On the other hand, from the bottom dead center state of the take-up lever shown by the solid line in Figure 12,
Until the top pin reaches the top dead center state shown by the solid line in Figure 0,
That is, when the hook 66 returns from the needle 24 side to the swing shaft 30 side, it is sufficient for the bushing 64 to rotate around the main shaft 43 by an amount corresponding to the angle θ2. Here, θ1〉θ
This is the relationship of 2.

Therefore, the hook 66 returns quickly and returns in a short time.

(Effects) In the present embodiment described above, even if the timing belt 77 becomes loose, if the adjustment screw 84 of the belt tension adjustment device 8 is further turned, the elastic deformation portion 83 will be deformed.
Projection piece 8 with screw hole 822 screwed into adjustment screw 84
21 is displaced in the vertical direction and tries to separate from the bed 101 of the bed housing 10. Therefore, the tension roller 820 pushes the timing belt 77, and the timing belt 77 becomes tense. Therefore, the timing belt 7
7 from loosening, the rotation of the large timing gear 73 can be reliably transmitted to the small timing gear 78, and the rotation of the hook 7 and the needle bar arm 2 can be prevented.
This is advantageous in ensuring synchronicity between the upper thread and the lower thread. Moreover, even if the adjustment screw 84 is turned once, the adjustment -
The screw 84 advances only one pitch. In other words, adjustment screw 8
The 91-node screw 84 advances only Q, 5 mm in one rotation of 4, and the height position of the tension roller 820 can be finely adjusted.

In the sewing machine according to this embodiment, the holding portion 82 of the bracket 80 is U-shaped to ensure strength, so even if an overload is applied to the timing belt 77, the tension roller 820 will not shift easily, and the timing belt 77 can be prevented from being damaged.

Further, in this embodiment, the lower surface of the bed housing 10 of the housing 1 is open, as shown in FIG. 3, which is a bottom view with the bed cover removed. Therefore, if the user operates the adjustment screw 84 from the bottom opening of the housing 1,
Adjusting the tension of the timing belt 77 can be easily performed.

Furthermore, in this embodiment, since the needle bar arm 2 is configured to swing relative to the housing 1 around the swing wheel 30, the sewing machine is The overall height can be reduced. In particular, since the length of the horizontally long arm portion 20 of the needle bar arm 2 is long, the distance from the axis of the swing shaft 30, which is the center of swing, to the needle 24 can be increased, so that the needle 24 can be directed toward the needle insertion hole 140. It is possible to have a large radius of curvature when swinging, which is advantageous for inserting the needle 24 perpendicularly into the needle insertion hole 140. In the present embodiment described above, the needle bar arm 2 is connected to the swing shaft 30 as described above.
Compared to conventional sewing machines in which the vertical needle bar moves back and forth in the vertical direction,
This is advantageous in shortening the needle bar 22, the inertial mass of the needle bar 22 is correspondingly reduced, and even when the needle bar arm 2 swings at high speed, it is advantageous in reducing vibration and noise of the sewing machine. Therefore, it is advantageous for high-speed operation of the sewing machine.

[Effects of the Invention] In the sewing machine according to the present invention, even if the endless belt becomes loose, the tension roller pushes the endless belt through the deformation of the deformation part by the deformation adjustment part of the belt tension adjustment device, and the endless belt is loosened. The belt is tense. Therefore, loosening of the endless belt can be prevented, and rotation of the first pulley can be reliably transmitted to the second pulley. Moreover, in the sewing machine according to the present invention, when the deformation adjustment section is composed of an adjustment screw and a female threaded hole, the adjustment screw advances only one pitch with one rotation of the adjustment screw, and the height position of the tension roller can be finely adjusted. It is advantageous for

In the sewing machine according to the present invention, when the needle bar arm is formed of a horizontally long horizontally long arm portion and a rising portion that is low in height and can freely swing, the length of the horizontally long arm portion is long and the height of the rising portion is small. Since the needle is low, it is possible to lower the height of the sewing machine and increase the radius of curvature when the needle swings toward the fabric, which is advantageous for inserting the needle perpendicularly into the fabric.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a perspective view of the entire sewing machine, Fig. 2 is an exploded perspective view of main parts, Fig. 3 is a bottom view of the sewing machine with the bed cover removed, and Fig. 4 is a perspective view of the entire sewing machine. The figure is a sectional view taken along the line rV-rV in FIG. 3, FIG. 5 is a sectional view taken along the line v-v in FIG. 3, FIG. Figure 7 is a top view, Figure 10 is a side view showing the top dead center of the take up, Figure 11 is a side view showing the needle bar reading bottom dead center, and Figure 12 is a side view showing the bottom dead center of the take up. be. In the figure, 1 is a housing, 10 is a bed housing, 11
1 is an arm housing, 12 is a top cover, 14 is a throat plate, 140 is a needle insertion hole, 2 is a needle bar arm, 20 is an oblong arm part, 21 is a rising part, 22 is a needle bar, 24 is a needle, 30 is a swinging part Shaft, 43 is the main shaft, 44 is the take-up crank, 45 is the needle bar arm crank, 6 is the take-up, 63 is the take-up shaft, 7 is the hook, 73
is a large timing gear (first pulley), 77 is a timing belt (endless belt), 78 is a small timing gear (second pulley), 79 is a hook shaft, 8 is a belt tension adjustment device, 80 is a bracket, 81 is a fixed part , 810a is a set screw, 82 is a holding portion, 820 is a tension roller, 821
83 is a protrusion, 83 is a deformation portion, 830 is a slit, and 84 is an adjustment screw (deformation adjustment portion). Patent applicant: Aisin Seiki Co., Ltd. Patent attorney: Hiroshi Okawa

Claims (1)

[Claims] (1) A housing, a needle bar arm built into the housing that operates the upper thread, a hook that operates the bobbin thread, a main shaft that operates the needle bar arm, a hook shaft that operates the hook, and a main shaft and hook shaft that are connected. The operating section includes a first pulley attached to the main shaft side, a second pulley attached to the rotary hook shaft side, and the first pulley attached to the hook shaft side.
It has an endless belt stretched around the outer circumference of the pulley and the outer circumference of the second pulley, and a belt tension adjustment device that adjusts the tension of the endless belt, and the belt tension adjustment device has a tension roller and a tension roller at one end. A bracket consisting of a holding part that rotatably holds the tension roller, and a deformed part whose other end is a fixed part fixed to the housing and is provided between the one end and the fixed part, and the holding part. A sewing machine having a belt tension adjustment device, comprising a deformation adjustment section that moves relative to the housing.