JPS641156B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a presser foot lifting device for a sewing machine, and more particularly to its presser foot lifting mechanism and needle thread adjuster.

In general, the presser foot lifting mechanism of a sewing machine presses the workpiece against the throat plate with a predetermined pressure during sewing, and removes the presser foot pressure when the sewing machine stops or when the workpiece is attached to or removed from the throat plate. The main part of the lifting mechanism is housed within the arm of the sewing machine head. The upper thread adjuster is a device that reduces the tension of the upper thread when the presser foot pressure is removed by the operation of the presser foot lifting mechanism or when the thread trimming mechanism is activated, and is the main part of this device. is installed outside the arm of the sewing machine head.

The method for operating the presser foot lifting mechanism is as follows:
Generally, there are two methods: a manual operation by the sewing worker and a knee operation method. When the presser foot lifting mechanism is operated by these methods to raise the presser foot to a predetermined height, it is necessary to operate the upper thread adjuster at the same time.
This is to reduce the tension of the needle thread and make it easier to pull out the needle thread when attaching and detaching the sewing item, but for the same reason, the needle thread adjuster is also operated during the thread trimming operation.

The configurations of the presser foot lifting mechanism, upper thread adjuster, and thread trimming mechanism will be explained below with reference to the drawings.

1 and 2 are an end view and an exploded perspective view of a sewing machine head showing a conventional presser foot lifting mechanism and upper thread adjuster, and FIG. It is a partially exploded perspective view showing a lever.

First, the configuration of a conventional presser foot lifting mechanism and upper thread adjuster will be explained based on these figures. 2 is an arm of the sewing machine head, 4 is a metal fixed to this arm 2 with a screw 3, and 1 is a metal A presser bar is movably fitted, 5 is a presser part fixed to the lower part of the presser bar 1 with a screw 6, and 7 is a slide provided at the upper part of the presser bar 1, and is protruded from the side thereof. The presser foot lifting cam 11 is engaged with the arm 10 that has been moved. Reference numeral 12 designates a shaft of the presser foot lifting cam 11, the end of which passes through the outside of the arm 2, and a manual lever 14 is fixed outside the arm via an O-link 13 with a spring washer 15 and a screw 16. A twist spring 17 is inserted between the presser foot lifting cam 11 and the arm 2 to hold the presser foot lifting cam 11 in a predetermined position, and a screw 8 is fitted to the upper part of the presser bar 1 extending upward from the slider 7.
20 is a thumbscrew provided on arm 2, 18 is this thumbscrew 2.
0 and the presser bar holder 8, 19 is a guide rod passed through this knob spring 18, and one end of the guide rod is inserted into the hole 21 in the axial direction provided in the presser bar 1. The other end is fitted into the thumbscrew 20. Therefore, when the thumbscrew 20 is rotated and the guide rod 19 is advanced downward,
The helical spring 18 is compressed and increases the pressure on the presser bar 1.

Further, 23 is a lifting plate attached to the arm 10 of the slider 7 with a stepped screw 22, 25 is a crankshaft whose tip is loosely fitted into an oval-shaped hole 24 provided in this lifting plate 23, and 26 is a This axis 2
An arm is fixed to the other end of 5 with a screw 27, 29 is an operating rod whose hook-shaped bent portion is inserted into the cylindrical hole 28 of arm 26 and fixed with a snap pin 30, and 31 is the other operating rod 29. A knee-raiser pin connected to one end and supported by an oil pan (not shown); 32 is a knee-raiser arm provided at the other end of this knee-raiser pin 31; 33 is an axis of this knee-raiser arm 32, one end of which has a joint 34
A knee operation plate 36 is provided via a connecting rod 35.

As described above, the presser foot lifting mechanism mainly includes the presser bar 1, the presser part 5, the slider 7, the presser bar holder 8, the spiral spring 18, the guide rod 19, the thumbscrew 20, etc., and the presser foot lifting cam 11 is operated by hand. , the manual lever 14, etc., and the knee operation is performed through the lifting plate 23, the shaft 25, the operating rod 29, the knee raising arm 32, the knee operating plate 36, etc.

On the other hand, a protrusion 37 is provided on the back of the slider 7, and an upper thread loosening lever 38 is attached to this protrusion 37.
arm 39 is engaged. The needle thread loosening lever 38 is attached to the arm 2 by a stepped screw 40, and the base of the other arm 41 is supported by the arm 2 by a conical spring 42. The tip of the arm 41 is in contact with the hemispherical tip of a pin 43 for loosening the needle thread. This pin 43 is fitted into a bush 44 fixed to the arm 2, and the other end passes through the outside of the arm 2. An O-link 45 is fitted into the stepped portion of the bush 44. A thread take-up spring 46 is inserted around the pin 43 in the cylindrical hole of the bush 44, and the tip of a tension rod 47 is fitted into the inner diameter of the thread take-up spring 46. The other end of the tension rod 47 is formed into a fork-shaped split screw 48. The other end of the pin 43 passes through a hole formed in the axis of the tension rod 47 and projects into the interior of the split screw 48. Two tension discs 49, 49, a tension disc holder 50, a conical spring 51, and a detent 52 are fitted in order on the outer periphery of the split screw 48, and tightened with a tension nut 53. Since the adjustment plate holder 50 has two buttonhole-shaped holes, the other end of the pin 43 is pressed at the center of the adjustment plate holder 50. Also, the upper thread supplied from the outside of the sewing machine is passed through two tension discs 4.
9 and 49, an appropriate tension is applied to the needle thread between the tension plate and the needle. As mentioned above, the upper thread adjuster mainly includes the upper thread loosening lever 38, the pin 43, the bush 44,
Tone rod 47, tone plate 49, 49, tone plate presser 5
0, conical spring 51, detent 52, tension nut 5
It is composed of 3 etc.

Another arm 54 of the upper thread loosening lever 38 is engaged with an end of a pin 55. The other end of this beam 55 is the hole 57 of the bell crank 56.
is engaged with. This bell crank 56 is a bell crank plate 5 screwed to the inner wall of the arm 2.
8 with a caulking pin 59. The tip of a flexible wire 61 is connected to the arm 60 of the bell crank. The tip of the covering portion 62 of the flexible wire 61 is fixed to the arm 63 of the bell crank plate 58. The other end of the flexible wire 61 passes through a hole 66 made in the arm 65 of the lever 64, and bushes 67, 67 are attached and fixed with screws 68, 68, as shown in FIG. The lever 64 is supported by a lever shaft 69 fixed to the arm 2. Further, a link 71 is connected to the other end of the lever 64 by a stepped screw 70. An arm 72 provided at the other end of this link 71 is in contact with the tip of a plunger 74 of a solenoid 73. Although not shown, an upper swing shaft for driving the thread cutting operation is inserted into a fork 75 provided at the upper end of the lever 64. Two arms are fixed to this upper swing axis,
One is opposed to a cam fixed to the upper shaft, and the other is connected to a connecting rod. A lower swing shaft having a thread cutting knife fixed to the tip thereof is connected to the other end of the connecting rod via an arm. The thread trimming mechanism mainly includes the lever 64, link 71, solenoid 73, and upper and lower swing shafts (not shown).
It consists of an arm, a cam, a connecting rod, a knife, etc.

Next, the functions of the presser foot lifting mechanism and the upper thread adjuster will be explained. First, a case will be described in which the presser foot lifting mechanism is manually operated when attaching and detaching a sewing product to and from the throat plate. When the manual lever 14 is lifted, the presser foot lifting cam 11 rotates, and the arm 10 is lifted in accordance with the lifting height of the cam. Since this arm is integral with the slider 7 fixed to the presser bar 1, as the arm 10 is lifted, the presser bar holder 8 is also lifted. Since this presser bar is fixed to the presser bar 1, the presser bar is lifted against the compression spring force of the helical spring 18. When the manual lever 14 is fully lifted,
Since the cam shaft 12 rotates 90 degrees and supports the arm 10 on the horizontal contour surface of the presser foot lifting cam 11, the presser foot portion 5 is held at a predetermined height above the throat plate (not shown). On the other hand, since the arm 39 of the upper thread loosening lever 38 is engaged with the protrusion 37 provided on the back surface of the slider 7, when the slider is lifted, the upper thread loosening lever 38
also rotates around the stepped screw 40. When the upper thread loosening lever 38 rotates, the upper thread loosening lever arm 4
1 presses the pin 43. Since the compression spring force of the conical spring 51 is acting on the other end of this pin via the tension plate holder 50, the pin 43 is displaced against this spring force. The above pin 43 resists the spring force.
When the tone plate 4 is displaced, the tone plate 4 is moved through the tone plate holder 50.
Since the compression spring force of the conical spring 51 acting on the needle threads 9 and 49 is removed, the tension on the needle thread is reduced.

In addition, when using the knee operation, the operation plate 36 can be operated with the knee.
By applying an external force to the above, the operation plate 36 rotates the knee raising shaft 33. When this knee-raising shaft rotates, the knee-raising pin 31 and the operating rod 29 are lifted. When this operating rod is lifted, the crankshaft 2
5 rotates, and the crank part of the shaft loosely fitted into the hole 24 of the lifting plate 23
pull up. This lifting plate has stepped screws 22
Since it is connected to the arm 10 of the slider 7 by the above-mentioned pulling up, the slider 7 is also pulled up. When the slider 7 is pulled up, the presser foot 5 is pulled up to a predetermined height above the throat plate in the same manner as in the manual operation described above, and at the same time, the tension of the needle thread is reduced by the displacement of the pin 43. In the case of knee operation, the presser foot 5 is maintained at a predetermined height only while the operation plate 36 is being pressed, and the tension of the upper thread is reduced.

When thread trimming is to be carried out, first, the solenoid 73 is powered on. When power is applied to the solenoid 73, the plunger 74 protrudes,
The ring 71 is displaced in the direction of arrow (A) as shown in FIG. When the link 71 is displaced, the lever 64 rotates around the lever shaft 69, and its fork 75 is indicated by the arrow (B).
Rotate in the direction. When the fork 75 is displaced, the upper swing shaft (not shown) is displaced in the axial direction, and the roller (not shown) attached to the tip of the arm is inserted into the groove of the cam (not shown). The upper swing shaft swings with the rotation of. The operation of the upper swing shaft is transmitted to the thread cutting knife (not shown) via a connecting rod (not shown), an arm (not shown), and a lower swing shaft (not shown), and the thread is cut. be done. On the other hand, the above lever 64 is an arrow
When rotated in the direction (B), the flexible wire 61 is pulled and displaced in the direction of the arrow (C), as shown in FIG. Since the tip of the flexible wire 61 is connected to the arm 60 of the bell crank 56,
As the flexible wire is displaced, the bell crank 56 rotates around the caulking pin 59. In the hole 57 provided at the other end of the bell crank 56,
Since the needle thread adjuster is connected via the scale ring 55, the needle thread loosening lever 38 rotates around the stepped screw 40 as the bell crank rotates.
When the upper thread loosening lever 38 rotates, the tension on the upper thread is reduced in the same manner as in the manual or knee operation described above.

In the presser foot lifting mechanism and upper thread adjuster of the conventional sewing machine described above, the objective function is whether the presser foot lifting mechanism is activated by hand or knee operation or the thread trimming mechanism is activated. Although they have a common feature of operating the needle thread adjuster and loosening the needle thread, they are constructed as independent mechanisms, which is extremely irrational.

In other words, in order to operate the upper thread adjuster when the presser foot lifting mechanism is operated by hand or knee operation,
A complicated upper thread loosening lever 38 is required, which is separate from the presser foot lifting cam 11 and the lifting plate 23, and when the thread trimming mechanism is activated, the slider 7 and the upper thread loosening lever 38 are attached to the crankshaft 25 and the lifting plate 23. In contrast to the mechanism that is connected and operated, there is a needle thread tension adjustment mechanism that includes a flexible wire 61, a bell crank 56, a pin 55, and a needle thread loosening lever 38. This is not only extremely unreasonable because the number of parts is large and the mechanism is complicated, but also because there is little space in the head of the sewing machine, the large number of parts reduces assembly efficiency and is extremely unreasonable. It's the economy.

This invention has been made in view of the above-mentioned drawbacks, and aims to simplify the mechanism for operating the upper thread regulator when the presser foot lifting mechanism is activated by hand or knee operation, and also to simplify the mechanism for operating the upper thread regulator when the presser foot lifting mechanism is operated by hand or knee operation, and also to improve the mechanism for operating the upper thread adjuster when the presser foot lifting mechanism is operated by hand or knee operation. By reversing the direction of rotation of the lever for loosening the upper thread, the present invention attempts to provide a presser foot lifting device in which the presser foot lifting mechanism can be shared by knee operation or thread cutting.

4 and 5 are views corresponding to FIGS. 1 and 2 showing the presser foot lifting mechanism and upper thread adjuster according to the present invention, and FIG. 6 is a view showing the lever according to the invention, and FIG. 8 is a diagram showing a stepped pin according to the invention, FIG. 8 is a diagram showing a presser foot lifting lever according to the invention, and FIG. 9 is a structural diagram showing a presser plate according to the invention.

The configuration of the presser foot lifting device according to the present invention will be explained below based on these figures. Note that the same reference numerals as in FIGS. 1 to 3 indicate the same or equivalent components as those in those figures, and detailed description thereof will be omitted.

In FIGS. 4 and 5, reference numeral 76 is a presser bar, the arm of which is fitted into a groove-shaped guide provided on the inner wall of the arm 2. As shown in FIGS. This presser bar holder 76 is fixed to the upper end of the presser bar 1 by a screw 77. The lower side of the presser bar 76 (fourth
In the case shown in the figure), the presser foot lifting cam 78 is engaged. This presser foot lifting cam 78 is fixed to a stepped portion of a stepped shaft 79 with a nut 80. Further, a presser plate 81 is attached to a screw 82 at the tip of the stepped shaft 79.
It is fixed by. The other end of the stepped shaft 79 passes through the outside of the arm 2, and a manual lever 83 is fixed thereto with a screw 84. On the inner wall of the arm 2, adjacent to the stepped shaft 79, an L-shaped leaf spring 85 made of a metal plate or the like is attached to a screw 86,
It is fixed at 86. Mainly, the presser bar 1, the presser part 5, the presser bar holder 76, the spiral spring 18, the guide rod 19, the thumbscrew 20, and the presser foot lifter 78,
The manual lever 83 and the like constitute a manual presser foot lifting mechanism of the present invention.

On the other hand, a presser foot lifting lever 8 is attached to the inner wall of the arm 2.
7 is attached with stepped screws 88. The arm 89 of the presser foot lifting lever 87 is attached close to the presser foot lifting cam 78 in a state where it engages with the presser foot holder 76. The tip of a connecting rod 91 is connected to the other arm 90 of the presser foot lifting lever 87 by a stepped screw 92. A hook-shaped upper end portion of an operating rod 95 passed through a groove 94 of the lever 93 is inserted into the hole at the other end of the connecting rod 91 and connected with a nut 96. As shown in FIG. 6, the groove 94 of the lever is a circular arc portion 98 having an average radius (r) around the fulcrum hole (o).
and a vertical portion 97 having a length (D) connected to the lower end thereof, and the width of the groove 94 is selected to be slightly larger than the outer diameter of the operating rod 95. Further, the horizontal length (E), vertical length (F), and average radius (r) of the circular arc portion 98 of the groove 94 are selected to be appropriate amounts based on the relationship with the stroke of the connecting rod 91. Furthermore, the groove 94 is a fulcrum hole (o)
The flexible wire 611 is provided on the displacement direction side (on the right side in FIG. 6) with respect to a vertical line passing through the flexible wire 611. That is, the distance (G) is selected between the center line (M) passing through the fulcrum hole (o) and the center line (N) of the vertical portion 97 of the groove 94. As shown in FIG. 5, the lever 93 is
It is attached to the inner wall of the arm 2 at the fulcrum hole (o) with a stepped screw 99. Furthermore, a stopper pin 100 for regulating the movement of the lever 93 and the other end of a coil spring 102 engaged with a hole 101 provided at the upper end of the lever 93 are attached to the inner wall of the arm 2. A similar coil spring 103 is also attached between the upper end of the operating rod 95 and the inner wall of the arm 2. In normal conditions (without knee operation),
The lever 93 is pressed against the pin 100 by the tension spring force of the coil spring 102, and the upper end of the operating rod 95 is positioned at the lower end of the vertical portion 97 of the groove 94 by its own weight and the tension spring force of the coil spring 103. ing. Mainly, the presser bar 1, the presser part 5, the presser bar holder 76, the spiral spring 18, the guide rod 19, the thumbscrew 20, etc., the presser foot lifting lever 87, the connecting rod 91, the lever 93, the operating rod 95, the knee raising pin 3.
1. The knee-lifting arm 32, the knee-lifting shaft 33, the joint 34, the arm 35, the knee-operating plate 36, etc. constitute a presser foot lifting mechanism by knee operation.

104 is a stepped pin that operates the upper thread adjuster, and its tip is connected to the pressing surface 1 of the presser foot lifting lever 87.
It is facing 05. This stepped pin 104 is made of metal and is made of a cylindrical rod or a square rod, the tip of which is formed into a curved surface such as a hemispherical shape, and a retaining ring 106 or a nut is fitted to the shaft portion, as shown in FIG. It forms a stepped section. This retaining ring or nut is opposed to and engaged with the presser plate 81 of the presser foot lifting cam 78. A needle thread adjuster is connected to the other end of the stepped pin 104, as in the conventional case.

The pressing surface 105 of the presser foot lifting lever 87 is the eighth
As shown in the figure, two V-shaped curved surfaces 107,
It consists of 107. Above stepped pin 10
In the normal state (knee operation or thread trimming is not activated), the tip of No. 4 is in contact with the pressing surface 1.
Located in the center of 05, there are two curved surfaces 107, 107
, that is, the center of the pressing surface 105 .

The presser plate 81 of the presser foot lifting cam 78 is made of a disk made of metal or the like, and as shown in FIG.
is provided. This protrusion is formed by press working or the like.

This is mainly performed by the presser foot lifting lever 87 or the presser plate 81, the stepped pin 104, the bush 44, the tension rod 47, the tension discs 49, 49, the tension disc presser 50, the conical spring 51, the detent 52, the tension nut 53, etc. An inventive needle thread regulator is constructed.

In this invention, the connection with the thread cutting mechanism is the fifth
Two screws 1 are attached to the upper end of the lever 93 as shown in the figure.
09, 109 and a flexible wire 111 fixed by a bush 110. This flexible wire covering portion 112 is fixed within the arm 2. A conventional thread cutting mechanism is connected to the flexible wire.

Next, the functions of the presser foot lifting mechanism and upper thread adjuster according to the present invention will be explained. First, when the manual lever 83 is lifted manually, the presser foot lifting cam 78 rotates, and the presser foot bar 1 is lifted together with the presser rod holder 76. As the presser foot lifting cam 78 rotates, the protrusion 108 of the presser plate 81 presses the retaining ring 106 of the stepped pin 104 and the side surface of the stepped portion of the nut. Therefore, the stepped pin 104
is displaced in the axial direction in accordance with the thickness of the protrusion 108 of the holding plate 81. When the stepped pin 104 is displaced, the needle thread adjuster is actuated in a conventional manner and the needle thread tension is reduced. Note that when the presser foot lifting cam 78 is at a predetermined rotational position, the leaf spring 85
It is held in a predetermined rotational position by the spring force.

On the other hand, when the knee operation plate 36 is rotated by knee operation, the operation rod 95 is pressed and the upper end portion is displaced along the groove 94 of the lever 93. At this time, since the lever is being pulled by the coil spring 102, the pin 1
00 and does not rotate. Therefore, when the upper end of the operating rod 95 is displaced along the groove 94, since the upper end of the operating rod 95 and the end of the connecting rod 91 are configured as a pair, the connecting rod 91
is pulled, and the arm 90 of the presser foot lifting lever 87 is rotated by a predetermined amount around the fulcrum. When the presser foot lifting lever 87 rotates, the arm 89 lifts the presser foot 76.
is lifted up. At the same time, presser foot lifting lever 8
The pressing surface 105 of No. 7 presses the tip of the stepped pin 104. Therefore, the stepped pin 104 is displaced in the axial direction corresponding to the curved surface 107 of the pressing surface 105. The upper thread regulator is then operated in the same manner as before.

Next, regarding the case where thread cutting is performed, the mechanism by which the flexible wire 111 is pulled in the direction of arrow (C) is exactly the same as the conventional one. When the flexible wire 111 is pulled, the connecting rod 91 is pressed as the lever 93 rotates, and the arm 90 of the presser foot lifting lever 87
(C) is rotated in the opposite direction (counterclockwise in FIG. 5). When the presser foot lifting lever rotates in this direction, the stepped pin 10 moves against the pressing surface 105.
The position of the tip of the presser foot 4 changes, and the tip comes to be pressed against the curved surface 107 of the presser foot lifting lever 87. Therefore, the stepped pin 104 is displaced,
Upper thread tension is reduced.

In the embodiments described above, the tip of the stepped pin 104 is opposed to the pressing surface of the presser foot lifting lever 87, but as shown in FIG. The same effect can be obtained by supporting the presser foot lifting cam 115 and pressing the tip of the stepped pin 114 with the pressing surface 117 of the presser foot lifting cam 116. In this case, as shown in FIG. 11, the presser foot lifting lever 113 is provided with an arc-shaped hole 119 centered on a fixed fulcrum, and a V-shaped curved surface 120 is formed on this surface. The stepped pin 1 shown in FIG. 12 is inserted into this hole 119.
Fourteen stepped portions 115 are supported. A presser plate 81 shown in FIG. 9 is attached to the end surface of the presser foot lifting cam 116.
A protrusion similar to the protrusion 108 provided in is provided.

Further, it is more preferable that a cylindrical roller be fitted to the hook-shaped upper end of the operating rod 95 in order to reduce friction with the lever 93. As described above, according to the present invention, the upper thread adjuster is operated to reduce the tension of the upper thread when the presser foot is released from the sewing material, and the upper thread adjuster is also operated when the thread trimming mechanism is operated. In a sewing machine that reduces the tension of the upper thread, a spring 18 is provided which constantly presses the presser foot 5 in the direction of pressing the sewn product, and a spring 18 which is interposed between the spring and the presser foot and is connected to the presser foot. It is rotatably provided and has a presser bar 76 that is displaced together with the presser section, a pin 104 that is moved to weaken the tension of the upper thread of the upper thread adjuster, an arm 89 and a pressing surface 105. When rotating in one direction, the arm is engaged with the presser foot bar, and the presser foot is moved in a direction away from the sewing material against the pressure of the spring, and the pin is pressed by the pressing surface. The tension of the upper thread of the upper thread adjuster is weakened, and when the upper thread adjuster rotates in a second direction opposite to the first direction, the presser foot is pressed by the spring without engaging the arm with the presser foot bar. The presser foot lifting lever 87 is configured to hold the presser foot in a position where it presses against the sewing material, and press the pin with the pressing surface to weaken the tension of the needle thread of the needle thread regulator.
The presser foot lifting lever is connected to the presser foot lifting lever, and when the presser foot is released from the sewing material, the presser foot lifting lever is displaced in a first direction, and when the thread trimming mechanism is operating, the presser foot lifting lever is rotated in a second direction. Since the connecting rod 91 is provided with a connecting rod 91 that is displaced so as to rotate in the direction of can contribute to the operation of the presser foot lifting lever 87.
When the presser foot is released from the sewing material, the presser foot is raised, and when the thread trimming mechanism is operated, the presser foot remains lowered, so that the lifting of the presser foot and the thread cutting operation can be carried out without any hindrance. It is something that can be done without any problems. Furthermore, if the presser foot lifting lever 87 is provided, the connecting rod 91 can also be shared. Such a common mechanism is not only rational, but also simplifies the mechanism in the sewing machine head, where there is limited space, which improves assembly efficiency and is economical.

[Brief explanation of drawings]

Figures 1 and 2 are an end view and a partially exploded perspective view of a sewing machine head showing a conventional presser foot lifting mechanism and upper thread adjuster, and Figure 3 is a partially exploded view showing a solenoid and lever that operate the thread trimming mechanism. FIG.
4 to 9 are diagrams for explaining one embodiment of the presser foot lifting device according to the present invention, and FIGS. 4 and 5 are diagrams corresponding to FIGS. 1 and 2, and FIG. FIG. 7 is a structural diagram of the lever, FIG. 7 is a structural diagram of the stepped pin, FIG. 8 is a structural diagram of the presser foot lifting lever, and FIG. 9 is a structural diagram of the presser plate. 10 to 12 are diagrams for explaining other embodiments of the present invention, in which FIG. 10 is similar to FIG. 4, FIG. 11 is similar to FIG. 8, and FIG. 12 is similar to FIG. 7.
FIG. In the figure, 1 is a presser bar, 5 is a presser part, 8, 76 are presser bars, 11, 78 are presser foot lifting cams, 14, 8
3 is a manual lever, 29 and 95 are operating rods, 36 is a knee operation plate, 38 is an upper thread loosening lever, 49 is a tension plate, 55 is a bell crank, 56 is a bell crank, 81
is the presser foot plate, 87, 113 is the presser foot lifting lever, 91
is a connecting rod, 93 is a lever, 94 is a groove, 104,1
14 is a stepped pin. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A sewing machine that operates an upper thread adjuster to reduce the tension of the upper thread when the presser foot is released from the sewing material, and also operates the upper thread adjuster to reduce the tension of the upper thread when the thread trimming mechanism is operated, a spring 18 that constantly presses the presser section 5 in the direction of pressing the sewing product; a presser bar 76 that is interposed between the spring and the presser section, is connected to the presser section, and is displaced together with the presser section; , a pin 104 of the needle thread adjuster that is moved to reduce tension on the needle thread.
and has an arm 89 and a pressing surface 105, and is rotatably provided, and when rotating in the first direction, the arm is engaged with the presser bar, and the presser part is sewn against the pressure of the spring. The pin is moved in a direction away from the object and the pin is pressed by the pressing surface to weaken the tension of the needle thread of the needle thread adjuster.
When rotating in a second direction opposite to the above direction, the arm is not engaged with the presser foot bar, and the presser foot is held in a position where it presses the sewing material by the pressure of the spring, and the pin is pressed against the sewing material. A presser foot lifting lever 87 is connected to the presser foot lifting lever 87, which is pressed by a surface to weaken the tension of the upper thread of the upper thread regulator, and is connected to the presser foot lifting lever 87 to release the presser foot from the sewing material. A presser foot lifting device for a sewing machine, comprising a connecting rod 91 that is displaced to rotate the presser foot lifting lever in a second direction when the thread trimming mechanism is in operation. .