JPH0773638B2 - Lower thread guide device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a guide device for a lower thread supply position corresponding to a stitch of a lock stitch sewing machine that can perform zigzag stitching and straight stitching.

(Prior Art) Straight stitches in a lockstitch sewing machine include a normal stitch as shown in FIG. 24 and a hitch stitch as shown in FIG. 25. When mixed, the stitches are disturbed as shown in FIG. In general, it is desired to sew with a normal stitch that causes no untwisting of the sewing thread. Normal stitches and hitch stitches are generated as shown in FIG. 29 and FIG. 30. Various stitches are generated for the bobbin thread drawn from the bobbin thread holding means.
It depends on whether the needle falls to the left or right when viewed from the front of the sewing direction. Generally, when the sword tip of the rotating hook is in a state where the bobbin thread comes to the front side of the bobbin thread withdrawal point when viewed from the front in the traveling direction of the sewing machine, that is, the left side of the needle, the stitch becomes a normal stitch in the route as shown in FIGS. When the lower thread comes to the rear side of the lower thread withdrawal point, that is, to the right side of the needle, a hitch stitch is made in the route as shown in FIG. Therefore, in general, when the bobbin thread supply source is viewed from the front in the traveling direction of the sewing machine as shown in FIG. 29, the bobbin thread is pulled out in order to come to the front side of the bobbin thread drawing point, that is, the left side of the needle. It is effective to feed the lower thread from the left side as shown in Fig. 32a, and many sewing machines avoid hitch stitches by this method. However, in such a system, in the zigzag sewing shown in FIG. 27, the phenomenon that the lower thread is offset occurs. This phenomenon is remarkable when the stitch pitch is small, and in order to eliminate this phenomenon and obtain a stitch without deviation as shown in FIG.
As shown in the figure, it is necessary to set the bobbin thread withdrawal point at the center of the zigzag stitch swing width.

(Problems to be Solved by the Invention) As described above, a different position between the straight thread sewing and the zigzag sewing is the proper position, and it is desirable to set the position to that position. On the other hand, the applicant of the present invention
In a sewing machine in which the bobbin thread draw-out port is the center of the swing in No. 4, a moving member that sets the bobbin thread draw-out port to the left during linear sewing is connected to the pattern selection section and the bobbin thread is selected when linear sewing is selected. It is shown that it engages with and guides to the left.

In the conventional example, the guide member is moved left and right by selecting a pattern to directly act on the bobbin thread to guide the bobbin thread drawing port, and it is possible to clearly switch the bobbin thread drawing port. However, regarding the release of the bobbin thread when switching from straight stitch to zigzag stitch, the moving member does not directly control the bobbin thread, and the bobbin thread return depends on the thread withdrawing action when forming the stitches. Therefore, when the zigzag sewing is selected, the moving member remains in the thread removal path of the upper thread, and the shape and finish are restricted. However, the present invention provides an improved device in these respects.

(Means for Solving Problems) According to the present invention, in a sewing machine capable of selecting zigzag stitching and linear stitching, the lower thread operating member is connected to the pattern selecting device to operate the lower thread to operate the lower thread. Position setting means for selectively setting the first position for engaging the lower thread guide wall on the fixed side and the second position for unmoving the lower thread with the lower thread or removing the lower thread from the lower thread guide wall. A lower thread guide wall for guiding the lower thread withdrawing position from the needle thread catching means is provided in the fixed portion on the lower thread path between the needle thread catching means and the needle hole of the needle plate, and the lower thread actuating member is It is designed to separate from the bobbin thread when the thread is actuated.

(Operation) Regarding "zigzag sewing", the zigzag sewing is selected by the pattern selecting device, the position setting means is operated to engage the lower thread, and the lower thread is engaged with the lower thread guide wall on the fixed side to lower the thread. The thread withdrawal position is supplied from a central position that conforms to the "zigzag stitch", and for the "straight stitch", the straight stitch is selected by the pattern selection device and the position setting means is operated to disengage from the lower thread. By retracting the lower thread from the lower thread guide wall, the lower thread is supplied from the lower thread withdrawing port of the lower thread catching means set to the left of the leftmost point of the width of the needle.

(Example) Next, the Example of this invention is described in detail with reference to drawings. First
In FIG. 6 to FIG. 6, reference numeral 1 denotes a hook serving as needle thread catching means, which is rotatably supported on the sewing machine frame 2 and is also rotatably and vertically movable on the sewing machine frame 2. A lock stitch is formed in cooperation with the needle 3 that is fixed to the tip of (not shown). An inner hook 4 for holding a lower thread winding 5 as a lower thread holding means is held in the hook 1 by a rotation preventing member (not shown) so as to prevent rotation. The lower thread withdrawing port 4a for withdrawing the lower thread from the lower thread winding 5 is set to the left of the leftmost point L of the swing port of the needle 3. Reference numeral 6 denotes a lower thread guide plate fixed to the step portion of the inner hook 4, and the lower thread guide wall 6a of the vertical rising portion thereof is set so as to coincide with the center position E of the swing of the needle when fixed. The upper surface 6b of the lower thread guide plate has substantially the same height as the upper surface 4b of the inner hook 4, and the lower thread guide wall 6a and the upper surface 6b of the rising portion are rounded so that the lower thread can be smoothly moved. Connected in shape. Reference numeral 7 denotes a lower thread feeding lever which is fitted and fixed to a feeding shaft 8 which is rotatably supported by the sewing machine frame 2 and a bridge portion 7a at the tip thereof is connected to a wall 4c of a step portion of the inner hook 4. It is arranged between the lower thread guide plate 6 and the lower thread guide plate 6.

As shown in FIG. 1, the driving means of the bobbin thread delivering lever 7 is connected to a driving shaft (not shown) supported by the sewing machine frame 2 by a transmission means, and a cam 10 is fixed to a lower shaft 9 which is rotationally transmitted. The other end of the bifurcated rod 11 having the bifurcated portion 11a fitted to the cam is fixed to the headed pin 14 fitted to the hole provided at the tip of the link 13 fixed to the feeding shaft 8. ing.

A pin 12 is fixed in the middle of the forked rod, and the pin and the cam groove 15a of the adjustment cam 15 rotatably supported by the headed pin fixed to the sewing machine frame 2 are fitted together.

The lower end 15b of the adjusting cam is arranged so that the plunger tip 16a of the solenoid 16 fixed to the sewing machine frame contacts the upper surface 15c of the adjusting cam 15 and the sewing machine frame 2.
The coil spring 18 is engaged with the coil spring 18 and always urges it in the direction of arrow A. The solenoid 16 is electrically connected to a pattern selection device (not shown) mounted on the operation surface of the sewing machine frame 2.

Next, the bobbin thread, the guide, and the operation in this embodiment will be described. When "straight stitch" is selected by the pattern selection device, the electrically connected solenoid 16 is excited and the fifth
As shown by the solid line in the figure, the plunger tip 16a of the solenoid is in the first position where the lower surface 15b of the adjusting cam 15 is pushed up. The cam groove 15a of the adjusting cam is tilted, and the pin 12 of the forked rod 11 is engaged with the cam groove, and the cam 10 fixed to the lower shaft 9 connected to the drive shaft (not shown) is rotated. The fulcrum position of the movement of the bifurcated rod 11 due to is changed, the movement range of the link 13 is changed, and the bridge portion 17 of the bobbin thread delivering lever 7 is moved to the uppermost point indicated by the solid line in FIG.
a, drive in the range where the lowest point is 17c. The uppermost point 17a is located above the lower thread path connecting the inner hook 4, the needle plate 50, and the needle hole 50a, and does not touch the lower thread. Lowest point
17c is a position where the lower thread is pulled into the position indicated by the alternate long and short dash line in the figure.
The lower thread path from the bridge portion 17 to the needle hole 50a is guided by the upper surface 6b of the lower thread guide plate 6, and the planar path of the lower thread is on the left side of the inner hook 4 as shown in FIG. Lower thread outlet
Since the bobbin thread from 4a is a perfect stitch, it is always on the left side of the leftmost point of the amplitude of the needle 3 and in front of the needle, that is, on the operator side from the needle. In the straight stitch, the phase where the perfect stitch and the hitch stitch are divided includes the phase where the needle thread and the needle tip of the stitch cross when the needle is descending from the top dead center and the needle tip reaches the cloth. During this time, the bridge 17 of the lower feeding lever 7 is 17a.
Is set in the vicinity of the uppermost point, and is then fed to the position 17c to be guided by the rising portion of the bobbin thread guide plate 6 so that the bobbin thread outlet is at the center position. Since there is a position 17a before and after the determination phase of, the bobbin thread 51 has the rising portion 6a of the bobbin thread guide plate 6.
It is a lower thread route drawn out from a lower thread outlet provided in advance in the inner hook 4 as shown by the solid line in FIG. The positional relationship is suitable for perfect stitching.

When the zigzag sewing is selected by the pattern selecting device, the solenoid 16 electrically connected to the zigzag sewing is excited by the pattern selecting device, and the plunger 16a moves to the position shown by the dotted line in FIG. The force causes the adjusting cam 15 to move to the second position shown by the dotted line. The movement of the pin 12 of the bifurcated rod 11 engaging with the cam groove 15a of the adjusting cam changes the movement of the cam 10 via the bifurcated rod 11 and the link 13 of the bobbin thread feeding lever 7. The bridge 17 has a top position 17b and a bottom position 17c in FIG.

That is, when "zigzag sewing" is selected, the uppermost position 17b, the lowermost position 1
7d, the lower surface of the bridge is the rising surface 6a of the lower thread guide plate 6.
The needle hole 50a of the needle plate 50 is located at a lower position and passes through the bridge portion 17 of the bobbin thread delivering lever 7 from the inner hook 4.
At the right needle drop position R of the needle swing range, the lower thread 51 is drawn to the right of the rising portion of the lower thread guide plate 6 as shown by the dotted line in FIG. The movement of the lower thread guide plate 6 to the left is restricted by the rising portion of the lower thread guide plate 6 and the lower thread is always pulled out from the central position.

Next, a second embodiment of the present invention will be described. As shown in FIG. 7, in the second embodiment, the operating range of the lower feeding lever 7 is changed by operating the adjusting cam 15. The operation of the adjusting cam 15 is performed by exciting the solenoid 16 connected to the pattern selecting device in the first embodiment, but in the present embodiment, the adjusting cam 55 replacing the adjusting cam 15 is used.
In place of the solenoid 16, a stepping motor that operates for each stitch is used.

Since the configuration other than the adjustment cam 15 and the stepping motor is the same as that of the first embodiment, the description thereof will be omitted.

In FIG. 7, a stepping motor 19 is fixed to the machine frame 2 of the sewing machine, and is also housed in the machine frame 2 of the sewing machine, and is connected to a swing control section which is connected to the pattern selecting device. An adjusting cam shaft 20 is rotatably supported by the sewing machine frame 2, and an adjusting cam 55 is fixed to one end of the adjusting cam shaft. An arm 21 is fixed to the other end of the adjusting cam shaft 20, and the other end of a link 22 fitted to a pin fixed to the tip of the adjustment cam shaft 20 is fixed to an arm 23 fixed to the output shaft of the stepping motor 19. It is fitted and connected to the pin 24.

Next, the guide of the lower thread will be described. When "straight stitch" is selected by the pattern selection device, the stepping motor is selected.
By rotating 19 to rotate the adjusting cam 55, the adjusting cam 55 is set to the first position shown by the solid line in FIG. The rotation setting position of the adjusting cam is determined by the movement of the bifurcated rod 11 such that the cam groove 55a of the adjusting cam 55 into which the pin 12 fixed in the middle of the bifurcated rod fits is inclined as shown in the figure. Tip 11b of the bifurcated rod 11
The swing amount of the link 13 connected to the bridge 13 is increased, and the bridge 17 at the tip of the bobbin thread delivering lever 7 is provided via the delivering shaft 8.
The operating range of is moved in the range between the uppermost point position 17a and the lowermost point position 17c as shown by the solid line in FIG. The uppermost point position 17a is located above the upper surface of the lower thread guide plate 6, and the lower thread pulled out from the inner hook 4 and guided to the upper surface 4b of the inner hook contacts the lower thread guide plate 6. It is a position not to be set, and like the first embodiment,
The lower surface of the bridge 17 of the bobbin thread delivering lever 7 is located above the bobbin thread guide plate 6 when the needle is descending from the top dead center and until the crossing phase where the needle thread and the needle tip of the stitch intersect. After crossing, the bridge of the bobbin thread feeding lever 7 is at the lowest position 17
When the "straight stitch" is selected, the bobbin thread is pulled out from the thread bobbin thread withdrawing port 4a on the left side of the inner hook 4 when the "straight stitch" is selected, so that the width of the needle swings. The bobbin thread is always located on the left side of the needle drop regardless of the straight stitching at any position of the needle, and it is set at a position where it becomes a perfect stitch.

Next, "zigzag stitching" is selected by the pattern selection device, and the stepping motor 19 is correspondingly rotated to rotate the adjusting cam 55 for each stitch. That is, in the "zigzag sewing", when the needle drop is located at the left position of the swing, the stepping motor 19 is rotated to move the adjusting cam 55 to the seventh position.
The cam is held by rotating it to the second position indicated by the dotted line in the figure.
The link 13 does not rotate with respect to the movement of the bifurcated rod 11 due to the rotation of 10, but remains in a fixed position. The position is such that the bridge 17 at the tip of the bobbin thread delivering lever 7 is set to the position of 17b shown by the dotted line in FIG. Top 4b of 6
Below the lower thread, the lower thread is engaged with the lower thread guide wall 6a of the rising portion of the lower thread guide plate 6 to guide the lower thread from the lower thread drawing port as shown in FIG. Set to position. Incidentally, the stepping motor 19 is rotated with respect to the straight stitch following the zigzag in the pattern, and the adjusting cam 55 is set at the position shown by the dotted line in FIG. 31 to set the lower thread withdrawing position to the left.

Next, a third embodiment of the present invention will be described with reference to FIGS. 10 to 12. A needle that moves up and down, a hook 1 that cooperates with the needle to form a lock stitch, and an inner hook 4 in which a lower thread guide plate is fixed in the hook.
However, in the present embodiment, instead of the bobbin thread delivering lever 7, a bridge is provided in the feed dog to feed the bobbin thread to the upper and lower sides of the feed dog. It is done by motion. The adjusting mechanism for the withdrawal position of the lower thread corresponding to the sewing pattern is constructed as follows.

A guide body 28 is fixed to a guide shaft 27 that is rotatably supported by the sewing machine frame 2, and a bridge portion 29 provided at the tip of the guide body has a bridge portion 29 on the wall 4c of the inner hook 4 and the bobbin thread guide plate. It is arranged so as to be located between the first and second terminals. A guide arm 30 is fixed to the other end of the guide shaft 27, and is connected to a plunger 32 of a solenoid 31 fixed to the sewing machine frame 2 via a pin 35 fixed to the tip thereof. The solenoid 31 is electrically connected to the pattern selection device.

Next, the bobbin thread guiding operation of this embodiment will be described. The lower thread is drawn from the lower thread winding accommodated in the inner hook 4, passes over the upper surface 4b of the inner hook 4, passes under the bridge 29 of the guide body 28, and further under the bridge 26 of the feed dog 25. Is pulled out to the stitch side from the needle hole of the needle plate.

When "straight stitch" is selected by the pattern selecting device, the solenoid 31 connected to the selecting device is excited to push the plunger 32 in the direction of arrow B to connect the guide to the plunger tip. The arm 30 is pushed up and the guide shaft 27 is rotated to set the bridge 29 at the tip of the guide body 28 to the first position 29a shown by the solid line in FIG. The lower surface of the bridge is the upper surface 4b of the inner hook 4 and the upper surface 6b of the lower thread guide plate 6.
It is set above the line connecting with and the bobbin thread drawn out from the inner hook 4 is above the lower thread guide plate 6 fixed to the inner hook 4 and is not affected by the lower thread guide plate 6. Thus, the bobbin thread is always located on the left side of the needle drop regardless of the linear stitching at any position of the needle swing by being drawn out from the bobbin thread drawing port 4a provided on the left side of the inner hook 4. Position.

Next, when "zigzag sewing" is selected by the pattern selecting device, the solenoid 31 connected to the pattern selecting device is selected.
Is excited to pull in the plunger 32 in the direction opposite to the arrow B, pull down the guide arm 30 connected to the tip of the plunger, and rotate the guide shaft 27 to move the bridge 29 at the tip of the guide body 28. Figure 12 Set to the second position indicated by the dotted line. The lower surface of the bridge is below the upper surface 4b of the inner hook 4 and the lower thread guide plate 6, and the lower thread drawn out from the lower thread outlet 4a of the inner hook 4 is attached to the lower surface of the bridge 29. In combination, the lower thread guide wall 6a fixed to the inner hook 4 is engaged with and guided by the lower thread guide wall 6a of the rising portion of the lower thread guide plate 6 shown in FIG. The bobbin thread from the mouth is guided by the rising portion 6a to draw the bobbin thread from the center position of the amplitude of the needle.

Next, a fourth embodiment will be described with reference to FIGS. 13 to 14. A point that includes a needle that moves up and down and left and right, a hook 1 that cooperates with the needle to form a lock stitch, and an inner hook that holds a bobbin thread inside the hook and is prevented from rotating by a rotation stop member. However, in this embodiment, a guide wall is provided in the bridge portion of the feed dog for the purpose of guiding the lower thread and without mounting the lower thread guide plate on the inner hook. is there. The operating structure of the guide member that operates between the wall 4c of the inner hook 4 and the feed dog is the same as that of the third embodiment, and will not be described.
In this embodiment, instead of the lower thread guide plate for guiding the lower thread withdrawal position of the third embodiment, a feed dog which moves up and down as shown in FIG.
A lower thread guide wall 34a for guiding the lower thread is provided on the bridge 34a of 33 so as to hang downward from the bridge 34 at a position at the center of the amplitude of the needle 3, and further, the left end of the bridge and the guide wall.
34a was smoothly connected to the inclined surface 34b.

Next, the bobbin thread guiding operation of this embodiment will be described. As shown in FIG. 14, the bobbin thread is pulled out from the bobbin thread winding accommodated in the inner hook 4 and the inner hook 4 is pulled out from the lower thread pull-out port 4a to the inner hook upper surface 4b.
Passing under the bridge portion 29 of the guide body 28,
Further, it is drawn out from the needle hole of the needle plate by passing under the bridge portion 34 of the feed dog 33.

When "straight stitch" is selected by the pattern selection device,
As shown in FIG. 10, the solenoid 31 connected to the pattern selecting device is excited to retract the plunger 32 in the direction opposite to the arrow B to lower the guide arm 30 connected to the tip of the plunger. By rotating the guide shaft 27, the bridge 29 at the tip of the guide body 28 is moved to the first position shown by the solid line in FIG.
Set to 29b. The lower surface of the bridge 29 is located below the lower thread path connecting the upper surface 4b of the inner hook 4 and the lower surface of the bridge portion 34 of the feed dog 33, and is provided in the bridge portion 34 of the feed dog 33. The bobbin thread drawing port 4a located at a position not affected by the bobbin thread guide wall 34a and located on the left side of the leftmost position of the swing provided in the inner hook 4 as shown by the solid line in FIG.
Since the bobbin thread is pulled out from and supplied from the bobbin thread, the bobbin thread is always located on the left side of the needle drop regardless of the position of the straight stitch of the needle swing range.

Next, when "zigzag stitching" is selected by the pattern selecting device, the solenoid 31 connected to the pattern selecting device is excited to push the plunger 32 in the direction of arrow B to connect the guide to the plunger tip. A bridge portion at the tip of the guide body 28 by pushing up the arm 30 and rotating the guide shaft 27.
29 is set to the second position 29a shown by the dotted line in FIG. The lower surface of the bridge portion 29 is the upper surface 4b of the inner hook 4 and the feed dog.
It is above the lower thread path connecting the bridge portion 34 of 33 and does not act on the lower thread. Therefore, the lower thread is engaged with the bridge portion 34 of the feed dog 33 and guided to the lower thread guide surface 34a. That is, when the needle drop position on the right side of the swing range of the needle is set and the needle drop position on the left side is set, the lower thread is the bridge portion of the feed dog 33.
By engaging the lower thread guide surface 34a formed in 34, the movement to the left of the lower thread guide surface is restricted, and the lower thread withdrawing position is kept at the center of the swing. When the needle drop position at the start of sewing after switching from the straight stitch to the zigzag stitch is on the left side, it is engaged with the slope 34b of the bridge portion 34 at the position shown by the solid line in FIG. At the time of transition, it moves over the slope 34b to the right side of the bobbin thread guide surface 34a, and the bobbin thread withdrawing position is kept at the center position of the swing.

Next, a fifth embodiment will be described with reference to FIGS. 15 and 16. In the fifth embodiment, the lower thread guide wall provided on the bridge of the feed dog is used as the lower surface guide of the fourth embodiment to keep the needle at the lower thread withdrawal position in the "zigzag sewing" at the center position of the swing. On the other hand, a lower thread guide wall is not provided on the bridge of the feed dog, and only the lower thread is fed out by the bridge portion, and the guide body 28 is replaced between the lower thread holding device and the feed tooth to replace the lower thread guide wall. The guide body 35 having the above is provided. The operation structure of the guide body is the same as that of the fourth embodiment, and therefore its explanation is omitted.

The bridge portion 36 at the tip of the guide body disposed between the wall 4c of the inner hook 4 and the bridge 26 of the feed dog 25 is located at the center position of the amplitude of the needle as shown in FIG. Hanging guide wall 36
a is provided, and the lowermost position of the guide wall and the left end of the bridge portion are smoothly connected to each other to form a slope.

Next, the bobbin thread guiding operation of this embodiment will be described. The bobbin thread is drawn from the bobbin thread winding housed in the inner hook 4, is drawn from the lower thread outlet 4a of the inner hook 4, passes through the inner hook upper surface 4b, and is guided by the guide member.
It passes under the bridge 36 of 35 and further under the bridge 26 of the feed dog 25, and is drawn out from the needle hole of the needle plate.

When "straight stitch" is selected by the pattern selection device, the solenoid 31 connected to the pattern selection device is excited to push the plunger 32 in the direction of arrow B to connect the guide to the plunger tip. The arm 30 is pushed up to rotate the guide shaft 27, and the bridge portion 36 at the tip of the guide pair 35 is set to the first position 36c shown by the solid line in FIG. The lower surface of the bridge 36 is located above the lower thread path connecting the upper surface 4c of the inner hook 4 and the lower surface of the bridge portion 26 of the feed dog 25 and does not act on the lower thread. Therefore, as shown by the solid line in FIG. 8, the stitch is fed from the bobbin thread withdrawing port 4a provided on the left side of the inner hook 4 and is located on the left side of any position of the needle swing, forming a perfect stitch. It is a suitable position for.

Next, when "zigzag stitching" is selected by the pattern selecting device, the solenoid 31 connected to the pattern selecting device is excited to pull the plunger 32 in the direction opposite to the arrow B and the tip of the plunger is pulled. The guide arm 30 which is connected to the guide body 35 is pulled down to rotate the guide shaft 27 and
16 shows the bridge portion 36 at the tip of the second position 36 shown by the dotted line.
Set to d.

The lower surface of the bridge 36 is located below the lower thread path connecting the upper surface 4a of the inner hook 4 and the lower surface of the bridge 26 of the feed dog 25, and the lower thread pulled out from the inner hook 4 is The lower thread guide surface 36a is engaged with the lower surface of the bridge portion 36 of the guide body 35.
Will be guided to. That is, when the needle drop position on the right side of the swing range of the needle is set to the left side, the lower thread engages with the lower thread guide surface 36a formed on the bridge portion 36 of the guide body 35. Movement of the bobbin thread to the left of the guide surface is restricted and the bobbin thread withdrawing position is kept at the center position of the swing. If the needle drop position at the beginning of sewing after switching from "straight stitch" to "zigzag stitch" is on the left side, the slope of the bridge 36 at the position indicated by the solid line in Fig. 15
36b, and when moving to the right of the subsequent needle drop, moves over the slope 36b to the right of the lower thread guide surface 36a,
The bobbin thread withdrawal position is maintained at the center position of the swing for any subsequent needle drop position.

Next, a sixth embodiment will be described with reference to FIG. It is provided with a needle that moves up and down and swings to the left and right, and a shuttle 1 that cooperates with the needle to form a lock stitch, and that the shuttle is not provided with a lower thread guide plate. This is similar to the fifth embodiment.
In the present embodiment, the guide wall at the bobbin thread withdrawing position is provided on the wall in front of the needle hole of the needle plate which is the bobbin thread path.

As shown in FIG. 17, the wall of the needle hole 37a of the needle plate 37 has the needle plate thickness removed from the center to the right side of the needle swing range, and the lower thread guide surface that hangs down from the deleted position in the center. 37b is formed. Reference numeral 38 denotes a guide body, and a bridge 39 which is an arm portion extended in the feed direction over the range of the amplitude of the needle is formed at the tip of the guide body. As shown in FIG. 10, the guide body is connected to the pattern selecting device as in the fourth and fifth embodiments and is fixed to the guide shaft 27 which is operated by the pattern selection.
They are connected via 41, and are supported by a pair of engagement pieces 42 that sandwich the intermediate portion 38a of the guide body 38 from above and below.

The structure between the guide shaft and the pattern selecting device is the same as that of the fourth and fifth embodiments, and therefore will be omitted.

Next, the bobbin thread guiding operation of this embodiment will be described. The lower thread is drawn out from the lower thread winding housed in the inner hook as shown in FIG. 8, passes over the inner hook upper surface 4b of the inner hook 4, and bridges 39 of the guide body 38.
The needle hole is pulled out from below. When "straight stitch" is selected by the pattern selection device, the solenoid 31 connected to the pattern selection device is excited to push the plunger 32 in the direction of arrow B and connect it to the tip of the plunger. The guide arm 30 is pushed up and the guide shaft 27 is rotated to rotate the connecting arm 40 in the direction of arrow C to move the guide body 38 in a substantially horizontal direction to move the bridge 39 to the 17th position.
It is set to the first position 39a indicated by the solid line in the figure. The guide wall 37 formed on the needle plate 37 is located at the position closest to the needle hole on the lower surface of the bridge and below the lowest position of the wall in front of the needle hole.
At a position where the lower thread does not touch b, the lower thread 51 is pulled out from the lower thread outlet 4a provided on the left side of the inner hook 4 as shown by the solid line in FIG. It is a position that is suitable for perfect stitch formation at the position that is supplied from the left side.

Next, when "zigzag sewing" is selected by the pattern selecting device, the solenoid 31 connected to the pattern selecting device is selected.
Is excited to pull in the plunger 32 in the direction opposite to the arrow B, pull down the guide arm 30 connected to the tip of the plunger, and rotate the guide shaft 27 to move the connecting arm 40 into the arrow C.
The guide body 38 is moved in the opposite direction to move the guide body 38 in the horizontal direction to set the bridge 39 to the second position shown by the dotted line in FIG. The portion of the lower surface of the bridge closest to the needle hole is the needle plate.
It is moved forward of the guide wall 37b formed in 37, and is a position where it does not touch the 37 lower thread pulled out from the inner hook 4 and guided to the needle hole 37a. Therefore, the lower thread drawn out from the lower thread drawing port 4a provided on the left side of the inner hook 4 passes over the upper surface 4c of the inner hook and engages with the lower thread guide surface 37b formed on the needle plate 37.
That is, when the needle drop position on the right side of the swing range of the needle is set and the needle drop position on the left side is set, the lower thread engages with the lower thread guide surface of the needle plate and moves to the left side of the guide surface. Movement is restricted and the bobbin thread withdrawal position is kept at the center position of the swing.

When the needle drop position at the start of sewing after switching from "straight stitch" to "zigzag stitch" by the pattern selecting device is on the left side, it engages with the lower side of the needle plate at the position shown by the solid line in FIG. At the time of subsequent shift of the needle drop to the right side, the needle plate 37 moves to the right side beyond the bobbin thread guide surface 37b, and the bobbin thread withdrawing position after the transition is maintained at the center position of the swing.

Next, a seventh embodiment will be described with reference to FIGS. 21 to 23. In the present embodiment, "mixing of hitch stitches in straight stitches" handled by the present invention is mainly when the cloth feed amount is large, and another "screw of a lower thread in zigzag stitches" handled by the present invention is used. As shown in FIGS. 19 (a) and 19 (b), the problem is mainly caused when the cloth feed amount is small.
The position of the lower thread withdrawal port is controlled according to the cloth feed amount. An inner hook 4 that has a needle that moves up and down and swings to the left and right and a hook 1 that cooperates with the needle to form a lock stitch and that accommodates a bobbin thread winding 5 that is a lower thread holding means. Is held by being prevented from rotating by a rotation stopping member.

A bobbin thread drawing-out port 4a for drawing the bobbin thread from the bobbin thread winding 5 is set on the inner hook 4 on the left side of the leftmost position of the width of the needle. Further, the same bobbin thread guide plate 6 as in the first to fourth embodiments is fixed to the inner hook 4. Reference numeral 41 denotes a feed dog, which has a cam surface 41a on its lower surface. Reference numeral 42 denotes a lower thread guide body, which is fitted on a guide shaft 43 supported by the sewing machine frame 2 and has a tip formed in a rod shape, the lower surface of which is engaged with the lower thread and the upper surface of which is the lower surface of the feed dog 41. Of the bobbin thread guide body 42 is set to be in contact with the cam surface 41a of the feed dog 41 by the spring action of a spring 44 provided between the other end and the sewing machine frame 2. It is in abutting engagement with the surface 41a.

The movement trajectory of the feed dog 41 is as shown in FIG.
The locus shown by the dotted line in the figure is when the feed amount is small,
The locus shown by the solid line in the figure is when the feed amount is large.
When the bobbin thread withdrawal position is set to the center position of the swing of the needle against the deviation of the bobbin thread which is a problem when the feed amount is small, the movement of the feed dog is as shown in the locus of FIG. The cam surface 41 of the feed dog 41 at a position close to the shuttle 4
The value a is set low by engaging the tip 42a of the guide body 42 with the low surface 45 on the cloth feed side. The lower thread pulled out from the inner hook 4 is engaged with the lower surface of the tip of the guide body 42, so that the lower thread is engaged with the lower thread guide plate 6 fixed to the inner hook 4. Therefore, as shown by the dotted line in FIG. 8, the lower thread outlet port 4a of the inner hook 4 is
The lower thread pulled out from the lower thread guide plate 6 has a rising member 6a.
When the needle drop position on the right side of the swing range of the needle is set to the needle drop position on the left side by engaging with
It engages with the rising surface 6a and is restricted from moving to the left side of the rising surface and the bobbin thread withdrawing position is kept at the center position of the swing.

The bobbin thread withdrawal position against the mixture of the hitch stitch, which is a problem when the feed amount is large, moves between the position where the movement of the feed dog 41 is close to the inner hook 4 and the position away from the inner hook 4 as shown in the locus of FIG. However, in the straight stitch, the phase where the stitch is divided into the perfect stitch and the hitch stitch is when descending from the top dead center of the needle and includes the phase where the needle thread from the stitch intersects the needle tip The phase of the feed dog 41 is the position away from the inner hook 4 as shown in FIG. 23 and the phase shown in FIG. 23. As described above, the guide body 42 is engaged with the tip of the cam surface of the feed dog 41, and the cam surface 41a of the feed tooth 41 has a shape such that it is located at the tip side or higher position.
Since the tip of the bobbin abuts and engages with the cam surface and is positioned high, the bobbin thread drawn from the inner hook 4 is engaged with the lower surface of the guide body 42 or from the upper surface 6b of the bobbin thread guide plate 6. Will also be located above. The lower thread is supplied from the lower thread outlet 4a of the inner hook 4 on the left side of the leftmost position of the swing.

In the first, third, fourth, fifth and sixth embodiments described above, the electric means for operating the solenoid connected to the pattern selecting device is shown. Therefore, mechanical means may be used.

(Effect of the invention) As described above, according to the present invention, in the sewing machine which can be formed by selecting "straight stitch" and "zigzag stitch" by the pattern selecting device, the bobbin thread corresponding to the selected stitch By maintaining the respective positions by controlling the positions when engaging the drawing position with the lower thread guide wall provided at an appropriate fixed position in the sewing machine frame and when releasing it from the lower thread guide wall, the zigzag In “sewing”, the lower thread is engaged with the lower thread guide wall to set it at the center position of the swing to prevent the lower thread from shifting to one side and to perform “straight stitch”.
Then, the bobbin thread can be released and supplied from the bobbin thread outlet of the inner pot on the left side of the leftmost position of the swing to prevent pitch stitching.

In addition, in the position control of the bobbin thread, the bobbin thread guide wall is provided on the fixed side
Since the operating member is configured to be separated from the bobbin thread path when the bobbin thread is released, it is possible to prevent the influence on the stitch due to the interference with the bobbin thread.

[Brief description of drawings]

FIG. 1 is a perspective view of the lower thread guiding device of the first embodiment, FIG. 2 is a plan view of the lower thread holding device, FIG. 3 is a perspective view of the lower thread guiding plate, and FIG. 4 is a lower thread holding device. 5 is a perspective view of the lower thread adjusting cam, FIG. 6 is an explanatory view of the lower thread guiding operation, FIG. 7 is a perspective view of the lower thread guiding device of the second embodiment, and FIG. Is a plan view of the lower thread holding device, FIG. 9 is an explanatory view of the lower thread guiding operation, FIG. 10 is a perspective view of the lower thread guiding device of the third embodiment, and FIG.
11 is a perspective view of the feed dog, FIG. 12 is an explanatory view of the lower thread guiding operation, FIG. 13 is a feed tooth of the fourth embodiment, FIG. 14 is an explanatory view of the lower thread guiding operation, and FIG. FIG. 16 is a perspective view of the lower thread guiding portion, FIG. 16 is an explanatory view of the lower thread guiding operation, FIG. 17 is a perspective view of the lower thread guiding device of the sixth embodiment, and FIG. Fig. 19 is an explanatory view of the lower thread deviation state, Figs. 20 and 21 are feed dog loci, Fig. 22 is an explanatory view of the lower thread guiding operation when the feed amount is small, and Fig. 23 is a feed amount. Of the bobbin thread guiding operation when is large,
Fig. 24 is a perfect stitch, Fig. 25 is a hitch stitch, Fig. 26 is a stitch of a straight stitch in which a hitch stitch is mixed, and Fig. 27 is a stitch of a zigzag stitch with a deviation of the bobbin thread.
Fig. 28 is a stitch of zigzag stitches without unevenness of the bobbin thread, Fig. 29 is an explanatory diagram of the process of forming the stitch of perfect stitch, Fig. 30 is an explanatory diagram of the process of forming the stitch of hitch stitch, and Fig. 31 is 32A and 32B are explanatory views of the relationship between the swing of the needle and the withdrawal position of the lower thread, 3 is a needle, 1 is a hook as needle thread catching means, and 50 is a needle. A plate, 50a are needle holes, and 6a is a lower thread guide wall.

Claims (3)

[Claims] 1. A lower thread and a needle held by the needle thread catching means are held by a needle which is supported by a sewing machine frame and moves vertically and horizontally, and needle thread catching means which is supported by the sewing machine frame and rotates. In a sewing machine having a pattern selection device that forms a lock stitch with the needle thread and selectively changes the position of the stitch such as straight stitch or zigzag stitch, the sewing machine is connected to the pattern selection device and is connected by the needle thread catching means. Vertical for guiding the bobbin thread actuated by the actuating member by providing position setting means for selectively setting the actuating member in a first position in which the bobbin thread is pulled out and a second position in which the bobbin thread is inoperative. And a lower thread guide member comprising a lower thread guide wall and an inclined portion integrally formed with the lower thread guide wall. 2. A position setting means for changing and setting a lower thread feeding amount by changing an operation range of a bridge of a lower thread feeding lever which acts on a lower thread in a vertical direction. The bobbin thread guide device according to item 1. 3. The bobbin thread guiding device according to claim 1, wherein the position setting means sets the position corresponding to a needle drop position of a sewing pattern.