JPH09192371A - Sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-size and low-priced sewing machine with a mechanical thread passage control device with a function to set the timing pattern of restraining the hold of a needle thread to at least, three different types. SOLUTION: The restraining and releasing operation of a needle thread is performed by a thread handling area restraining plate 28 and a movable wheel 30, and a timing pattern for restraining and releasing the needle thread is set to at least, three different types. To materialize this timing process, either of the groove cam, breakage cam 42b or cam for Z 42c of a rotary cam 42 which is rotated concurrently with an upper shaft is selected. The switching operation for the release in timely manner is performed by a solenoid 56 and a Z motor 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread passing controllable sewing machine for restraining and releasing an upper thread by a pair of thread engaging bodies.

[0002]

2. Description of the Related Art Conventionally, as a sewing machine capable of controlling thread passage timing in three or more stages, there is a sewing machine disclosed in Japanese Patent Application No. 7-29115 filed by the present applicant. This is a mechanical thread passing mechanism in which the needle thread from the thread spool to the thread take-up is released during a predetermined period at the maximum thread take-up position of the thread take-up in synchronization with the rotation of the upper shaft of the sewing machine, while it is restrained during other periods. A control device is provided so that the needle thread required for the seam is fed out from the thread spool in conjunction with the cloth feed operation, and the thread tension is automatically adjusted with almost no adjustment of the thread tension pressure (upper thread tension) of the thread tension device. It is configured to be able to take. In addition, several types of sewing patterns and modes associated with sewing are categorized into three types, the thread release period of the needle thread that matches each is set, and classification is performed at three types of thread constraint release timing. doing.

[0003]

Attention is paid to the driving means for switching the thread restraint release timing, and in order to realize three kinds of thread restraint release timing, it is necessary to carry out three stages of drive switching. Yes, on and off 2
It cannot be realized by the switching drive means of step control. Therefore,
It is necessary to realize three-step switching by combining at least a plurality of on-off two-step controllable switching driving means or by adopting three or more controllable switching driving means, which requires a lot of space inside the sewing machine. Or costly. For this reason, a popular sewing machine equipped with a mechanical thread passage control device is required to be small in size and inexpensive, but
It becomes a large and expensive sewing machine.

The present invention has been made in order to solve the above-mentioned problems, and is equipped with a mechanical thread passage control device, and has three or more types of timing patterns for pinching and constraining the upper thread, while being small in size. The purpose is to provide an inexpensive sewing machine.

[0005]

In order to achieve this object, a sewing machine of the present invention has a needle swing drive for swinging a needle bar in a direction perpendicular to a cloth feed direction to generate a sewing pattern. Relative movement is possible between the device and the approach position where the upper thread is clamped and restrained between the thread supply source and the balance and the separated position where the upper thread is released in the thread supply path from the thread supply source to the eyelet of the sewing needle through the balance. Both thread engaging bodies are timed to the rotation of the sewing machine main spindle so that the pair of thread engaging bodies are separated from each other by a predetermined interval phase in the main spindle rotation phase of the sewing machine, and are close to each other in the other rotation phases. The thread passage control means for controlling the relative movement of the sewing machine, and the release timing switching means for changing the timing of switching the thread engaging bodies to the separated position by the thread passage control means by a predetermined phase angle of the sewing machine main shaft to switch the thread engagement body to at least three stages. Solution And a switching driving means for driving the timing switching means, further, the switching drive means, on and equipped with a 2-step switching drive switchable in two stages off, the switching of the release timing, Part 2
Both the step switching drive device and the needle swing drive device are driven.

Therefore, by using the already installed needle swing drive device as the drive means in combination with the two-stage switching drive device, a plurality of timing patterns for pinching and constraining the upper thread can be obtained while at least three types. It is possible to provide a small-sized and inexpensive sewing machine without the need to prepare the switching driving means or the expensive driving means that can be controlled in three or more steps.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments embodying a sewing machine of the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1 showing the internal mechanism of the sewing machine head, an upper shaft 14 is provided substantially rearward of a sewing machine upper shaft 14 (hereinafter referred to as the upper shaft) rotatably supported by a sewing machine frame 12 (hereinafter referred to as the machine frame). The balance support shaft 16 arranged in parallel is the machine frame 1
It is attached to 2. The balance 18 has a base end portion 18b rotatably supported by the balance support shaft 16, and a swing lever 18a from a base end portion 18b of a balance crank 20 fixed to a left end portion of the upper shaft 14. It extends to the left end face. The crank pin 21 of the balance crank 20 has a balance 18
It extends through to the left through an elongated cam hole formed in the rocking lever 18a, and is connected to the needle bar crank 22 and the needle bar 24. Further, the balance 18 is integrally formed with a balance main body formed in a crank shape from the swing lever 18a,
A thread holding portion 18c is formed on the upper end portion thereof.

When the upper shaft 14 rotates and the balance crank 20 and the crank pin 21 fixed to the upper shaft 14 rotate around the upper shaft 14, the swing lever 18a of the balance 18 is rotated.
With the cam hole shape, the swing lever 18a of the balance 18 reciprocally swings around the balance support shaft 16 as a swing center, and moves along the timing chart shown in FIG. 12 with the rotation phase of the upper shaft 14 as a parameter.

At this time, the needle bar 24 is also attached to the crank pin 21,
It reciprocates up and down via the needle bar crank 22 according to the timing chart shown in FIG. 12 with the rotational phase of the upper shaft 14 as a parameter. The phase angle of the timing chart shown in FIG. 12 is such that the uppermost position of the needle bar 24 is 0 °.

From the thread spool (not shown) to the thread holding portion 1 of the balance 18.
The upper thread from the thread spool to the thread holding portion 18c in the upper thread supply path extending from 8c to the eye hole 26a of the sewing needle 26 can be locked or released in synchronization with the rotation phase of the upper shaft 14. ,
The yarn path restricting plate 28, the movable wheel 30 (yarn engaging body), and yarn passage control means for controlling the approach and separation of these are provided as follows.

A thread guide plate 28 is fixed to the left side surface of a central front portion of the thread body 32, and a pin 32a extending leftward is fixed to the right end portion thereof. This pin 3
A first movable member 34 having a substantially U-shape in a front view is rotatably supported by 2a, and a second movable member 36 having a substantially U-shape in a front view is also rotatably supported inside thereof. There is. To the right side wall 34a of the first movable member 34, a movable wheel 30 that comes into contact with the yarn path regulating plate 28 from below is rotatably fixed. That is, the upper thread from the thread spool is threaded onto the thread path regulating plate 28 and the movable wheel 3.
It can be pinched and restrained between 0s.

A torsion spring 38 is mounted on the pin 32a, and one end of the torsion spring 38 is attached to the first movable member 34.
Is engaged with the spring bearing portion 34b of the thread guide member 32 and the other end thereof is engaged with the spring bearing portion 32b of the thread guide body 32. Therefore, in FIG. 2, the first movable member 34 is elastically biased in the counterclockwise direction with respect to the yarn path body 32, and the movable wheel 30 is always in contact with the yarn path regulation plate 28.
To abut. Further, the second movable member 36
A pin 40 is inserted between the left side wall and the right side wall of the first movable member 34, and a cylindrical rotation regulating member 40a is fixed to the right end portion of the pin 40, and the regulating portion 34c protrudes from the right side wall 34a of the first movable member 34. Are configured to come into contact with the rotation restricting member 40a.

A drive arm 36a extending rearward and obliquely upward is provided on the right side wall of the second movable member 36.
When the drive arm 36a rotates clockwise as shown in FIG. 8, the rotation restricting member 40a pushes up the restricting portion 34c, and the first movable member 34 and the second movable member 36 rotate clockwise. The upper thread is released from the restraint. When the drive arm 36a rotates counterclockwise as shown in FIG. 7, the second movable member 36 rotates counterclockwise, and the first movable member is also rotated counterclockwise by the spring force of the torsion spring 38. The upper thread is restrained by rotating in the direction.

As shown in FIGS. 7 and 8, the movable wheel 3 is
An annular V groove is formed on the peripheral surface of 0, and the yarn path regulating plate 28 is formed in an inverted U shape in a side view so as to engage with the V groove of the upper half of the movable wheel 30 from above. The yarn path restricting plate 28 is formed in a convex curved surface having a U-shaped cross section. Therefore, the upper thread from the thread spool is bent into a U-shape by the thread guide plate 28, and the balance 18
Since the needle thread extends through the eyelet 26a of the sewing needle 26 via the thread holding portion 18c, the upper thread is reliably restrained by the movable wheel 30 and the thread path restricting plate 28.

A rotating cam 42 is fixedly attached to the upper shaft 14 as a release timing switching means for timing the rotation of the upper shaft 14 to restrain and release the upper thread at a predetermined timing.
As shown in FIGS. 3 and 5, on the left side of the rotary cam 42, a circular cam groove having a small diameter for maintaining the state in which the movable wheel 30 is brought close to the yarn path regulating plate 28, and the movable wheel 30 are provided. A groove cam 42a is formed in combination with a cam groove including a circular portion having a diameter larger than that of the circular cam groove in order to separate it from the yarn path regulating plate 28.

A first opening / closing link 44 is disposed in a substantially U-shape in a front view diagonally upward and rearward of the upper shaft 14 with a width from a position with respect to the rotary cam 42 to a position corresponding to the thread body 32.
Further, a second opening / closing link 46 is disposed inward of the second opening / closing link 46 in a width of a position corresponding to the position slightly to the left from the position with respect to the rotary cam 42 in a substantially U-shape in a front view. The first opening / closing link 44 and the second opening / closing link 46 are arranged parallel to the upper shaft 14 in the machine frame 1.
It is rotatably supported by an opening / closing link shaft 48 fixed to 2. A pin is fixed to the base and tip of the right arm of the second opening / closing link 46, and the pin 46a at the tip is a groove cam 42a.
, And the base pin 46b is engaged with the hole 44a in the right arm of the first opening / closing link 44. The pin 44b at the tip of the left arm of the first opening / closing link 44 is rotatably and slidably connected to the upper end of the drive arm 36a. Second open / close link 46 Open / close link shaft 4 between the left and right arms
A torsion spring 49 is attached to the
Both ends of 9 are engaged with the first opening / closing link 44 and the second opening / closing link 46.

Therefore, the first opening / closing link 44 is elastically biased in the clockwise direction in FIG. 2 to be connected to the drive arm 36a, and the second opening / closing link 46 is elastically biased in the counterclockwise direction to be connected to the right arm tip pin 46a. Always comes into contact with the outer side wall of the groove cam 42a.

In the above yarn passage control device, the rotation cam 42 is rotated by the rotation of the upper shaft 14, and when the groove diameter of the groove cam 42a is changed from small to large, the second opening / closing link 46 is rotated counterclockwise. Then, the right arm root pin 46b of the second opening / closing link 46 pushes up the upper end surface of the hole 44a in the right arm of the first opening / closing link 44, and the first opening / closing link 44 rotates to drive arm 36a, that is, the second movable member. 36,
Then, the upper thread is released from the restrained state via the first movable member 34. Further, when the upper shaft 14 rotates and the groove diameter of the groove cam 42a goes through a constant state and changes from large to small, the second opening / closing link 46 rotates clockwise in the opposite direction. Then, the pushing force of the upper end surface of the right arm hole 44a of the first opening / closing link 44 of the right arm root pin 46b of the second opening / closing link 46 is released. At this time, the first opening / closing link 44 is also rotated in the opposite direction by the spring force of the torsion spring 38, and the upper thread is clamped and restrained. As shown in FIG. 12A, the movement curve of the movable wheel 30 of the straight stitch that releases or restrains the upper thread according to the groove cam 42a of the rotary cam 42 is shown.

As can be seen from FIG. 12, since the upper thread is restrained by the thread path regulating plate 28 and the movable wheel 30 when the upper thread is tightened when the balance 18 is raised from the lowermost position to the uppermost position, the upper thread Tightening is surely performed. On the other hand, when the phase angle advances to about 30 ° and the balance 18 reaches the uppermost position, the cloth feeding operation by the tooth feeding (not shown) is started. After that, when the phase angle reaches 40 ° with a delay of about 10 °, that is, with a delay of about 10 ° from the start of the cloth feeding operation, the restraint by the yarn path restricting plate 28 and the movable wheel 30 is released to supply the upper yarn. It Hereinafter, this timing will be referred to as a release timing at the time of straight line sewing. The necessary amount of upper thread due to the cloth feeding thereafter is supplied to the balance 18. Therefore, by the time the upper thread is released, there are two stages: tightening the upper thread by the balance 18 and tightening due to the shortage of the thread that should be consumed by the cloth feeding for about 10 ° until the upper thread is supplied. Tightening will be performed, and the tight seam required for straight stitching will be obtained.

Next, a release timing switching mechanism for setting the timing of releasing the upper thread during zigzag sewing and thread cutting to be earlier than the release timing during linear sewing will be described. On the right surface of the rotary cam 42 fixed to the upper shaft 14, a thread cutting cam 42 used when releasing the upper thread during thread cutting is provided.
b, Z cam 4 used when releasing the upper thread during zigzag sewing
Two types of external cams are formed, a circular cam 42d for 2c and a neutral cam (home position at the time of straight line sewing). The minimum diameter of these three cams is the same as that of the neutral circular cam 42d, but the outer diameter of the thread cutting cam 42b is about 140 °, and the outer diameter of the Z cam 42c is about 9 °.
An operating cam portion having a predetermined height over 0 ° is formed. The rotary cam 42 is formed on the left side of the actuating cam portion having a larger outer shape, and the groove cam 42a is formed on the opposite surface on the left side.

A solenoid holder 50 is fixed to the machine frame 12 above the rotary cam 42. The pair of shaft support portions of the solenoid holder 50 has a left-right operating shaft 5
2 is slidably and rotatably supported. Operating shaft 5
A second opening / closing link 54, which is U-shaped in a front view and engages with any of the three outer shape cams, is fixed to the second screw 2 with a screw. Further, the solenoid holder 50 is attached to the operating shaft 52.
A compression spring (not shown) is mounted between the left shaft support portion and the right arm of the third opening / closing link 54, and the right arm of the third opening / closing link 54 contacts the right side surface of the shaft support portion of the solenoid holder 50. The cam follower portion 54a at the tip of the arm portion that extends downward on the left side surface is constantly elastically biased so as to engage with the neutral circular cam 42d. At this time, the operating shaft 52 and the third opening / closing link 54
The position in the left-right direction of is the position for straight line.

On the other hand, in order to move the third opening / closing link 54 to the left to engage with the thread cutting cam 42b and the Z cam 42c, the solenoid holder 50 has a solenoid 56 for switching the release timing in the right direction. Is attached.
This solenoid 56 constitutes the two-stage switching drive device of the present invention. A pin 50a is erected on the solenoid holder 50 immediately below and right of the solenoid 56.
At 0a, a suction member 58 is rotatably supported. Further, a coil spring, which is weaker than the spring force of the compression spring, is attached to the pin 50a, and the suction member 58 has a tip portion 58 thereof.
a is elastically biased so as to always push the operating shaft 52 to the left.

Therefore, the attracting member 58 is always in the position pushed rightward by the actuating shaft 52 due to the balance of the spring force, and is rotated when attracted by the solenoid 56, and the tip 58a moves the actuating shaft 52 to the left. It is designed to slide in the direction. The solenoid 56 generates an attractive force by being excited,
When the suction member 58 is completely sucked by the plunger 56a, the tip end portion 58a of the suction member 58 is moved to the operating shaft 52.
Is pushed to the left, and the cam follower portion 54a of the third opening / closing link 54, which is screw-fixed to the operating shaft 52, is fixed at a position where it engages with the thread cutting cam 42b of the rotary cam 42. At this time, the operating shaft 52 and the third
The position of the opening / closing link 54 in the left-right direction is the thread cutting position.

Immediately to the right of the solenoid 56 is the pin 50
Another pin 50b is erected on the solenoid holder 50 on the back side of "a". A switching member 60 is rotatably supported on the pin 50b. The engaging portion 60a, which is one end of the switching member 60, is formed so as to engage with the stopper portion 58b of the suction member 58 so as to limit the rotation amount of the suction member 58. The cam follower portion 60b, which is the other tip portion, is engaged with the switching cam 64 on the back side of the Z motor 62, which is a needle swing drive device, and is always driven by a spring (not shown).
The b is elastically biased so as to come into contact with the switching cam 64. The switching cam 64 is fixed to the Z motor shaft so that it can rotate integrally with the Z motor shaft, and the outer shape is a cam, which is divided into a large diameter portion, a small diameter portion, and a connecting portion thereof.

As shown in FIG. 10, the cam follower portion 60b of the switching member 60 is engaged with the large diameter portion of the switching cam 64 during normal sewing. At this time, the engaging portion 60a is rotated to the position where the stopper portion 58b of the attracting member 58 is engaged, and the actuating shaft 52 is slid leftward. The cam follower portion 54a of the opening / closing link 54 is set at a position where it engages with the Z cam 42c of the rotary cam 42. The position of the operating shaft 52 and the third opening / closing link 54 in the left-right direction at this time is a zigzag (Z) position.

As shown in FIG. 11, when the Z motor 62 rotates by a predetermined amount and the small diameter portion of the switching cam 64 is brought into a position where it engages with the cam follower portion 60b of the switching member 60, the switching member 60 is counteracted by the spring force. Rotate clockwise. Then, the suction member 58 causes the plunger 56a of the solenoid 56 to move.
The engaging portion 60a of the switching member 60 and the stopper portion 58b of the attracting member 58 do not engage with each other even when rotated to the position where they are completely sucked. That is, only when the two conditions of the rotation of the Z motor 62 by a predetermined amount and the generation of the attraction force of the solenoid 56 overlap,
The suction member 58 is completely sucked by the plunger 56a,
The operating shaft 52 and the third opening / closing link 54 can be in the thread cutting position. These Z motor 62 and solenoid 56
Etc. constitute the switching drive means of the present invention.

On the contrary, as shown in FIG. 10, if the attraction force of the solenoid 56 is generated but the Z motor 62 does not rotate by a predetermined amount, the suction member 58 has its stopper portion 58b.
The amount of rotation is limited by the engagement of the engaging portion 60a of the switching member 60. Thereby, the operating shaft 52 and the third opening / closing link 5
4 is the Z position.

As shown in FIG. 9, if the attraction force of the solenoid 56 is not generated, the operating shaft 52 and the third opening / closing link 5
4 remains the position for straight lines.

Switching cam 64 that rotates in the same direction as the Z motor shaft
When the Z motor 62 is in the needle swing range by normal sewing (the needle swing width is 7 mm in the sewing machine of this embodiment, that is, the needle swing width on one side is 3.5 mm), the large diameter portion and the switching member 60 are
The cam follower portion 60b of is engaged. When the needle swing is overrun to a range not used in normal sewing (when the needle moves 5 mm to the left in the sewing machine of this embodiment), the small diameter portion and the cam follower portion 60b of the switching member 60 are set to engage with each other. Has been done.

A pin 44c having a distance slightly shorter than the distance between the first opening / closing link 44 and the left side surface of the third opening / closing link 54 is fixed to the rear of the right side surface of the first opening / closing link 44. When the third opening / closing link 54 moves from the linear position to the Z position or the thread cutting position, the lower end of the left side surface of the third opening / closing link 54 is in a position where the pin 44c can be pushed down. Further, as shown in FIG.
There is a slight gap in the pushing direction between c and the lower end of the left side surface of the third opening / closing link 54.

When the needle swing is within a normal swing width (within the range of 7 mm in the sewing machine of this embodiment), when the solenoid 56 is energized and excited, the third opening / closing link 54 moves from the linear position to the Z position. . When the upper shaft 14 is rotated, the third
The cam follower portion 54a of the opening / closing link 54 is the Z cam 4
Ride on the mountain part of 2c. The third opening / closing link 54 rotates counterclockwise, and the upper thread restraint state is released via the pin 44c, that is, the first opening / closing link 44, the second movable member 36, and the first movable member 34.

Further, the upper shaft 14 rotates and the Z cam 42
When the c-shaped portion ends, the third opening / closing link 54 rotates clockwise in the opposite direction to the above, and the upper thread is clamped and restrained by the spring force. FIG. 12B shows the movement curve of the movable wheel 30 in the zigzag stitch for releasing or restraining the upper thread according to the Z cam 42c of the rotary cam 42 as described above. However, at this time,
The second opening / closing link 46 also tries to rotate the first opening / closing link 44 by the groove cam 42a of the rotating cam 42. But,
As can be seen from the comparison between the A curve and the B curve in FIG. 12, the movable wheel 30 is opened by the Z cam 42c, that is, the B curve is performed about 10 ° earlier in the upper shaft rotation phase. At this time, the hole 44a in the right arm of the first opening / closing link 44 has a long hole shape so as to be able to move against the movement of the pin 46b at the base of the right arm of the second opening / closing link 46. For this reason,
The movable wheel 30 is controlled by the Z cam 42c. On the other hand, the cam curve for Z is formed so that the pinching and restraining operation is performed slightly earlier (1 ° to 2 ° in the upper shaft rotation phase) by the Z cam 42c than by the groove cam 42a. Therefore, the movable wheel 30 is controlled by the groove cam 42a, and the upper thread is clamped and restrained at the same timing as when the straight stitch is sewn.

As described above, when sewing the zigzag pattern, the upper thread is restrained by the thread path restricting plate 28 and the movable wheel 30 when tightening the upper thread which raises the balance 18 from the lowermost position to the uppermost position. The tightening of is surely executed. On the other hand, when the phase angle reaches approximately 30 °, the balance 18 reaches the uppermost position, the upper thread is tightened by the balance 18, and the cloth feeding operation is started. And the restraint by the movable wheel 30 is released. Hereinafter, this timing is referred to as the release timing when sewing the zigzag pattern. Therefore, the necessary amount of the upper thread due to the cloth feeding thereafter is supplied to the balance 18. The release timing for zigzag sewing is released about 10 ° earlier than the release timing for straight-line sewing, and the required amount of thread for cloth feeding is supplied in sufficient quantity, so that a stable and soft stitch can be obtained.

At the time of thread cutting, a thread cutting knife (not shown) located below the needle plate 84 moves a large stroke while hooking the upper thread and the lower thread, and cuts the thread by utilizing the moving speed. At this time, it is necessary to freely pull out the upper thread for the movement stroke of the thread trimming knife. The operation timing of this thread trimming knife is around 0 ° of the upper shaft rotation phase. Therefore, in the vicinity of the upper shaft rotation phase of 0 °, a larger amount of the upper thread is required for the thread trimming knife. When sewing is normally performed, the upper thread is clamped and restrained at the upper shaft rotation phase of 0 °, and if the thread trimming operation is performed in that state, the upper thread will be forcibly torn off, or the upper shaft Problems such as rotation being locked will occur. Therefore, it is necessary to provide an independent release timing for thread trimming, which is different from the release timing for straight stitching in which the upper thread is released at the upper shaft rotation phase of 0 ° for thread trimming and the release timing for zigzag sewing.

In the needle swinging operation, the tip of the sewing needle 26 is moved to the needle plate 46.
Then, after coming out of the sewing object (not shown) and further rising from the upper surface of the presser foot 86, it starts from about 280 ° in the upper shaft rotation phase. At the time of normal sewing, the stitching pattern is formed within 3.5 mm on one side by allocating the swing width to the center.
In the thread cutting operation, the solenoid 56 is first energized and excited.

When the upper shaft rotation phase reaches 280 °, the Z motor 62 is rotated so as to move the needle swing amount to the left side of the center by 5 mm. Then, as described above, as shown in FIG. 11, the third opening / closing link 54 moves from the straight position to the Z position to the thread cutting position. Upper shaft 1
When 4 rotates and the rotation phase advances to about 330 °, the cam follower portion 54a of the third opening / closing link 54 rides on the mountain portion of the thread cutting cam 42b. The third opening / closing link 54 rotates counterclockwise, and the upper thread restraint state is released via the pin 44c, that is, the first opening / closing link 44, the second movable member 36, and the first movable member 34. Therefore, the upper shaft rotation phase is 0
In the vicinity of ゜, the upper thread is the balance 18 and the eye 26 of the sewing needle 26.
A sufficient amount of thread for thread cutting passes through a and is drawn by a thread cutting knife (not shown).

Further, when the upper shaft 14 rotates and the rotation phase reaches about 60 °, the thread cutting ends, the sewing machine upper shaft 14 stops rotating, and the solenoid 56 is de-energized. At this time, since the tip of the sewing needle 26 is still raised from the upper surface of the presser foot 86, the needle swing position is returned to the position before the start of thread trimming within the range of 3.5 mm on one side by center distribution which is a normal sewing range. In this way, the thread cutting cam 42 of the rotary cam 42 is
The movement curve of the movable wheel 30 during the thread cutting operation for releasing the upper thread according to b is shown in C of FIG.

The control system of the sewing machine is constructed as shown in the block diagram of FIG. S / S switch 66 for instructing start / stop of the sewing operation, pattern selection switch 68 for selecting a desired pattern, thread trimming switch 70 for thread trimming when sewing is completed, and rotation phase of upper shaft 14 Stick 2
A timing signal generating device 72 for generating a pulse signal for each predetermined minute angle with reference to the uppermost position of 4 is connected to an input / output interface 74 of the control device. Further, the input / output interface 74 has a sewing machine motor 76 for driving the upper shaft 14 via a drive circuit,
The solenoid 56, the Z motor 62 and other various actuators (not shown) necessary for driving the sewing machine are connected. The control device is a CPU 78 and an input / output interface 74, a ROM 80 and a RAM 8 connected to the CPU 78.
The program memory of the ROM 80 stores a control program for controlling the entire sewing machine including each actuator.

In the sewing machine configured as described above,
Select a straight line pattern by operating the pattern selection switch 68 and press S /
When the S switch 66 is operated, the sewing machine motor 76 is driven by the start signal from the S / S switch 66 and the upper shaft 1
4 rotates. At this time, since the solenoid 56 is not driven to be excited, the third opening / closing link 54 is in the linear position in which the rotary cam 42 is engaged with the neutral circular cam 42d.
The balance 18 and the needle bar 24 are driven by the motion curve shown in FIG. 12, and at the same time, the movable wheel 30 is separated from the thread guide regulating plate 28 at the opening timing at the time of linear sewing with the upper shaft rotation phase angle of about 40 °. The movable wheel 30 approaches the yarn path regulating plate 28 again at an angle of about 115 °.

When the zigzag pattern other than the linear pattern is selected by operating the pattern selection switch 68 and the S / S switch 66 is operated, the sewing machine motor 76 is driven and the solenoid 56 is excited. Third open / close link 5
Reference numeral 4 denotes a Z position that is engaged with the Z cam 42c of the rotary cam 42. The movable wheel 30 is separated from the yarn path restricting plate 28 at the opening timing of the zigzag pattern sewing with the upper shaft rotation phase angle of about 30 °, and the movable wheel 30 approaches the yarn path restricting plate 28 again at the phase angle of about 115 °.

When it is desired to cut the thread after the sewing is finished, the thread cutting switch 70 is operated. In this case, the solenoid 56 is energized and excited simultaneously with the operation of the thread trimming switch 70, and the sewing machine motor 76 is driven to start the rotation of the upper shaft 14. The timing signal generator 72 detects the rotational phase of the upper shaft 14, and when the phase angle reaches 280 °, the Z motor 62 rotates by a predetermined angle. Then, the cam follower portion 60b of the switching member 60 is engaged with the small diameter portion of the switching cam 64, the suction member 58 is completely sucked by the plunger 56a, and the operating shaft 52 and the third opening / closing link 54 are at the thread cutting position. Can be Therefore, the third opening / closing link 5
The cam follower portion 54a of No. 4 engages with the thread cutting cam 42b of the rotary cam 42, and the movable wheel 30 is separated from the thread path regulating plate 28 at the opening timing at the time of thread cutting with the upper shaft rotation phase angle of about 330 °. .

As described above in detail, since the timing of releasing the upper thread is switched between the straight stitch and the zigzag stitch, the stitches which are automatically caught in the straight stitch when the pattern is selected are automatically changed in the zigzag stitch. A soft seam is obtained, and at the same time, automatic thread trimming by only button operation is possible, and an excellent sewing machine capable of switching the upper thread release timing in at least three stages can be realized. At the same time, the needle swing drive motor is used not only for the needle swing operation but also as a drive source for switching the needle thread release timing in three stages, and is used in combination with a simple solenoid that can only switch between two stages of on and off. As a result, the switching drive means can be made small and inexpensive.
Further, since the switching timing of three stages is obtained from one cam that rotates integrally with the upper shaft 14, the release timing switching means can be configured in a small size with a simple configuration.
Further, the grooved cam 42a on the right side of the cam and the three outer shape cams on the left side are formed deeper as the shape of the cam is larger, so that the cam can be formed only by simple resin molding of the top and bottom.

[0044]

As is apparent from the above description, according to the sewing machine of the present invention, the timing for releasing the upper thread restraint by the pair of thread engaging members is set by the thread passage control means and the opening timing switching means. Since more than two stages are provided and the switching drive can be set by the two-stage switching drive device and the needle swinging drive device, the upper thread is clamped even in the mechanical thread passage control device adopted in a popular sewing machine. It is possible to provide a small-sized and inexpensive sewing machine without having to prepare a plurality of switching driving means or an expensive driving means that can be controlled in three or more steps while setting at least three types of constraint timing patterns. .

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of a sewing machine according to an embodiment.

FIG. 2 is a left side view seen from the line AA in FIG.

FIG. 3 is an enlarged sectional view taken along line BB of FIG. 1;

FIG. 4 is an enlarged cross-sectional view taken along the line CC of FIG.

FIG. 5 is a left side view showing a relationship between a first opening link, a second opening link and a rotary cam.

FIG. 6 is a left side view showing a relationship between a first opening link, a third opening link and a rotary cam.

FIG. 7 is a diagram showing an upper thread restrained state by a thread engagement body and a thread passage control means.

FIG. 8 is a diagram showing an upper thread released state by a thread engagement body and a thread passage control means.

FIG. 9 is a view showing a release timing state at the time of linear sewing by the release timing switching means, the two-stage switching drive device and the needle swing drive device.

FIG. 10 is a diagram showing a release timing state at the time of zigzag sewing by a release timing switching means, a two-stage switching drive device and a needle swing drive device.

FIG. 11 is a diagram showing an opening timing state at the time of thread cutting by an opening timing switching means, a two-stage switching driving device, and a needle swinging driving device.

FIG. 12 is a timing chart showing the operation of each mechanism of the sewing machine.

FIG. 13 is a block diagram showing an electrical control configuration of the sewing machine.

[Explanation of symbols]

 14 Upper shaft 18 Balance 24 Needle bar 28 Thread guide plate 30 Movable wheel 34 First movable member 36 Second movable member 40 Pin 42 Rotating cam 44 First opening / closing link 46 Second opening / closing link 48 Open link shaft 50 Solenoid holder 52 Operation Axis 54 Third open / close link 56 Solenoid 58 Adsorbent 60 Switching member 62 Z motor 64 Switching cam

Claims (1)

[Claims] 1. A needle swinging drive device for swinging a needle bar in a direction perpendicular to a cloth feed direction to generate a sewing pattern, and a thread supply from a thread supply source through a balance to a stitch hole of a sewing needle. Between the inner thread supply source of the path and the balance, a pair of thread engaging bodies that are relatively movable between an approaching position where the upper thread is clamped and restrained and a spaced position where the upper thread is released, and a predetermined interval in the main shaft rotation phase of the sewing machine. Thread passing control means for controlling the relative movement of both thread engaging bodies in synchronism with the rotation of the sewing machine spindle so as to be the separated position during the phase and the approached position during the other rotational phases; Release timing switching means for changing the timing for switching the two thread engaging bodies to the separated position by a predetermined sewing machine spindle rotation phase angle and switching the timing by at least three steps by the thread passage control means, and switching for driving the release timing switching means. In the sewing machine having drive means, the switching drive means includes a two-stage switching drive device capable of switching between two stages of ON and OFF, and switching of the release timing is performed by the two-stage switching drive device and the needle swinging device. A sewing machine characterized by being driven by both drive devices.