JP2007202679A - Thread tension device of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of components, to facilitate the work of assembling the components, to improve responsiveness, to perform miniaturization and to lower costs. <P>SOLUTION: The thread tension device 1 of a sewing machine includes: a pair of thread tension discs 31 and 32 for clamping a thread; a disc presser 33 which can be abutted to one thread tension disc 31 and moved so as to attach and detach the thread tension disc 31 to/from the other thread tension disc 32; a driving mechanism 4 for driving the disc presser 33 so that one thread tension disc 31 approaches the other thread tension disc 32; and a drive source 5 provided inside a sewing machine head part frame 2 formed of a ferromagnetic material for driving the driving mechanism 4. The drive source 5 includes a needle 6 provided with permanent magnets 52 and 53 and a stator 7 provided with a coil 55 wound around the permanent magnets 52 and 53 at a prescribed interval. In the thread tension device 1, the sewing machine head part frame 2 is turned to the coil yoke of the coil 55. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

The sewing machine is provided with a thread tension device that applies an appropriate tension to the thread in order to prevent the thread from sagging.
As shown in FIG. 7, the thread tension device 100 is disposed on the front side (the right side in FIG. 7) of the sewing machine head frame 101. On the front side of the sewing machine head frame 101 is provided a balance 102 for tightening the thread by vertical movement, and the thread supplied from the thread supply source to the needle is passed through the balance 102 and then constitutes the thread tension device 100. An appropriate tension is applied by being sandwiched between the pair of thread tension plates 103 and 104. A solenoid 105 serving as a drive source for driving one thread tension plate 103 is provided on the back side of the sewing machine head frame 101, and the thread tension device 100 projects from the front side and the back side of the sewing machine head frame 101. ing. Inside the sewing machine head frame 101, an eccentric cam 106 provided on the main shaft and a needle bar 107 that moves up and down with the rotation of the main shaft are provided.
As shown in FIG. 8, in the thread tension device 100, one thread tension tray 103 can be brought into and out of contact with the other thread tension tray 104, and a dish presser 108 driven by a solenoid 105 has one thread tension tray 103. Is pressed toward the other thread tension tray 104, so that the thread can be clamped between one thread tension tray 103 and the other thread tension tray 104. The plate retainer 108 is provided with a drive rod 109 extending in the axial direction of the thread tension plates 103 and 104. One end of the drive rod 109 is driven by driving the output shaft 105a of the solenoid 105. The dish presser 108 can be driven (see, for example, Patent Document 1).

As shown in FIG. 9, in another type of thread tension device 120, a pair of thread tension plates 123 and 124 are attached to a base member 122 fixed to a solenoid 121 by a movable pin 125. The thread tension device 120 can change the force by which the plunger 130 of the solenoid 121 pulls the movable pin 125 toward the solenoid 121 by adjusting the current supplied to the solenoid 121, and the thread tension plate 123 is changed by the change in the force. , 124 can adjust the tension acting on the thread clamped.
As shown in FIG. 10, the solenoid 121 is provided with a coil frame 127 in a machine frame 126 made of a ferromagnetic material, and a coil 128 is provided in the coil frame 127. A plunger 130 to which a magnetic member 129 is fixed is provided in the machine casing 126. Plunger 130 is supported by bearings 131 and 132 so that it can move in the axial direction and cannot rotate. The magnetic member 129 fixed to the plunger 130 is formed in a cylindrical shape, and a stepped portion 129a having an enlarged diameter is formed in a part of the magnetic member 129 (see, for example, Patent Document 2).

FIG. 11 is a view showing the structure of the voice coil motor 140 in the thread tension device using a voice coil motor as a drive source.
In the voice coil motor 140, a cylindrical coil yoke 143 is provided in a mounting hole 142 formed in the sewing machine head frame 141 so as to be in close contact with the mounting hole 142 of the sewing machine head frame 141. A cylindrical coil bobbin 145 around which the coil 144 is wound is provided on the inner surface of the coil yoke 143. Inside the coil bobbin 145, there is provided a mover shaft 147 with a permanent magnet 146 attached around it. The mover shaft 147 is supported by a bearing 148 attached to the coil yoke 143 and the coil bobbin 145.
A magnetic flux 150 is generated by the permanent magnet 146 attached to the mover shaft 147 and the coil 144 is energized, whereby a thrust force that moves the thread tension plate is applied to the voice coil motor 140 in the axial direction of the mover shaft 147. Along the line.
Japanese Patent Laid-Open No. 2003-181182 JP 2000-202183 A

  However, in a drive source of a thread tension device such as the above-described solenoid or voice coil motor, a yoke having a complicated shape is required to form a magnetic circuit, resulting in increased component costs. In addition, the number of parts in the drive transmission path from the drive source to the thread tension plate is large, and the responsiveness of the drive source varies greatly depending on the tolerance and finish roughness when assembling each part, so that the thread can be clamped with appropriate tension. You may not be able to. In addition, as the number of parts increases, the weight increases and the responsiveness decreases, and there is a limit to downsizing.

  Accordingly, the present invention has been made to solve the above-described problems, and can reduce the number of components, thereby facilitating the assembly work of components, improving responsiveness, downsizing, and reducing costs. An object of the present invention is to provide a thread tension device for a sewing machine.

In order to solve the above-described problems, the invention described in claim 1 includes a pair of thread tension plates for holding the yarn and one thread so that one thread tension plate is brought into contact with and separated from the other thread tension plate. A plate presser that is movable in contact with the tension plate, a drive mechanism that drives the plate press so that one thread tension plate approaches the other thread tension plate, and a sewing machine head formed of a ferromagnetic material A drive source for driving the drive mechanism, and the drive source is wound around the permanent magnet with a predetermined interval around a mover provided with a permanent magnet. In a thread tension device for a sewing machine having a stator provided with a coil, the sewing machine head frame is a coil yoke of the coil.
Here, the ferromagnetic material means a material generally called a ferromagnetic material such as iron, cobalt, nickel and the like.

According to the first aspect of the present invention, when the drive mechanism is driven by the drive source, the drive mechanism drives the dish presser, and by driving the dish presser, one thread tension tray is moved relative to the other thread tension tray. Approach and pinch the thread.
Here, since the stator is provided with a coil and the coil yoke of this coil is carried by the sewing machine head frame, there is no need to provide the coil yoke of the coil separately from the sewing machine head frame as in the prior art.
Thereby, the number of parts of a drive source can be reduced. The drive source is provided in the sewing machine head frame. However, the number of parts can be reduced to facilitate the work when the drive source is assembled to the sewing machine frame. In addition, since the number of parts can be reduced, the drive source can be reduced in size, and downsizing can be realized to reduce the weight and improve the response of the drive source. Moreover, since the number of parts can be reduced, the cost for producing the drive source can be reduced.

  According to a second aspect of the present invention, in the thread tension device of the sewing machine according to the first aspect, a bearing of the movable element is provided on a coil bobbin in which the coil is accommodated.

According to the invention described in claim 2, the tolerance when assembling the mover is the tolerance when assembling between the machine head frame and the coil bobbin, and the tolerance when assembling between the coil bobbin and the bearing. Since only two locations need to be considered, it is less susceptible to tolerances during assembly than when a coil yoke is provided as in the prior art.
Therefore, the drive accuracy of the drive source can be improved.

  According to a third aspect of the present invention, in the thread tension device for a sewing machine according to the second aspect, the coil bobbin and the bearing are integrally formed.

  According to the invention described in claim 3, the number of parts of the drive source can be further reduced by integrally forming the coil bobbin and the bearing. In addition, the drive accuracy of the drive source can be further improved.

  According to the first aspect of the present invention, the number of parts of the drive source can be reduced. The drive source is provided in the sewing machine head frame. However, the number of parts can be reduced to facilitate the work when the drive source is assembled to the sewing machine frame. In addition, since the number of parts can be reduced, the drive source can be reduced in size, and downsizing can be realized to reduce the weight and improve the response of the drive source. Moreover, since the number of parts can be reduced, the cost for producing the drive source can be reduced.

  According to the invention described in claim 2, it is possible to improve the driving accuracy of the driving source.

  According to the invention described in claim 3, the number of parts of the drive source can be further reduced. In addition, the drive accuracy of the drive source can be further improved.

Hereinafter, the best mode of a thread tension device for a sewing machine will be described in detail with reference to the drawings.
<Configuration of sewing thread tension device>
As shown in FIGS. 1 and 2, a thread tension device 1 for a sewing machine is connected to a main shaft 11 driven by a sewing machine motor (not shown) and an eccentric cam 12 provided on the main shaft 11 via a link or the like. A needle bar 13 that moves up and down in synchronization with the rotation of 11, a balance 14 that tightens a thread by raising during sewing, and the like are provided on a sewing machine head frame 2 formed of a ferromagnetic material. Here, the ferromagnetic material means a material generally called a ferromagnetic material such as iron, cobalt, nickel and the like.
The thread tension device 1 is provided in the vicinity of the jaw portion of the sewing machine head frame 2 so as to penetrate from the front to the back, so that the thread passed through the balance 14 is clamped on the front side of the sewing machine head frame 2. It has become.

  The thread tension device 1 includes a thread tension device 3 that applies tension to a thread, and a drive rod as a drive mechanism that drives a dish presser 33 so that one thread tension tray 31 approaches the other thread tension tray 32. 4 and a voice coil motor 5 as a driving source for applying a driving force to the thread tensioner 3. The thread tension device 3 protrudes from the sewing machine head frame 2 on the front side of the sewing machine head frame 2 (the side facing the user when sewing). The voice coil motor 5 is provided inside the machine head frame 2 together with the main shaft 11, the needle bar 13, and the like and cannot be visually recognized. Only the lead wire 58 for supplying current to the voice coil motor 5 is provided. It only protrudes from the back side of the sewing machine head frame 2.

As shown in FIG. 3, the thread tension device 3 is movable so that a pair of thread tension plates 31 and 32 holding the yarn and one thread tension plate 31 are brought into contact with and separated from the other thread tension plate 32. And a plate holder 33.
The thread tension plates 31 and 32 are formed in a disc shape, and are arranged on the front side of the sewing machine head frame 2 along the moving direction of one of the thread tension plates 31. On the opposite side of the thread tension tray 31 from the side facing the thread tension tray 32, a dish presser 33 that presses the thread tension tray 31 so as to move the thread tension tray 31 toward the thread tension tray 32 is provided. .

The dish presser 33 is, for example, a plate material having three claw portions 33a, and is held by a dish presser holder 34 that prevents the dish presser 33 from rotating about its axis. Further, the pan presser 33 is positioned by a positioning collar 35 that positions the drive rod 4 with a screw 35a. The dish presser holder 34 is attached to the drive rod 4 by a screw 34a.
The pan presser 33 and the pan presser holder 34 are covered with a protective cover 36, and the protective cover 36 is attached to the pan presser holder 34 with screws 36a.
A thread tension bar 37 is attached to one end of the drive rod 4 by a thread tension bar base 38 and a screw 38a. A thread take-up spring 39 is provided on the thread tension bar 37 and the thread tension bar base 38. The thread take-up spring 39 is a torsion coil spring as a whole.

  The drive rod 4 connects the thread tension device 3 and the voice coil motor 5, transmits the drive of the voice coil motor 5 to the thread tension device 3, and drives the thread tension plate 31.

As shown in FIGS. 4 to 6, the voice coil motor 5 has a drive rod 4 inserted therein, is formed of a ferromagnetic material such as iron, and functions as a mover 6 of the voice coil motor 5. It has. Around the axis of the mover shaft 51, permanent magnets 52 and 53 are fixed side by side in the axial direction of the mover shaft 51 by an adhesive or the like. The permanent magnets 52 and 53 are made of a rare earth material such as a neodymium magnet or a samarium cobalt magnet, and are formed in a cylindrical shape as shown in FIG. Thus, the mover 6 of the voice coil motor 5 is configured by including the mover shaft 51 and the permanent magnets 52 and 53 provided on the mover shaft 51.
Here, as shown in FIG. 5 (b), the permanent magnet 52 is magnetized from the inner peripheral surface toward the outer peripheral surface along the radial direction, and the permanent magnet 53 is shown in FIG. 5 (c). It is magnetized from the outer peripheral surface toward the inner peripheral surface along the radial direction.

Around the axis of the permanent magnets 52 and 53, a cylindrical coil bobbin 54 made of a resin material for insulation is provided with a slight gap from the outer peripheral surface of the permanent magnets 52 and 53. The coil bobbin 54 is wound with a coil 55 that energizes a control current of the driving propulsion force of the voice coil motor 5 around the axis. That is, the coil bobbin 54 arranges the coil 55 at a predetermined interval with respect to the permanent magnets 52 and 53.
Here, the coil 55 is composed of a single winding, wound around a position facing the outer peripheral surface of the permanent magnet 52 and a position facing the outer peripheral surface of the permanent magnet 53, and winding around the permanent magnet 52. It is wound so that the direction and the winding direction around the permanent magnet 53 are opposite to each other. Thus, the stator 7 of the voice coil motor 5 is configured by including the coil bobbin 54 and the coil 55 wound around the coil bobbin 54.
With such a configuration, as shown in FIG. 6, a magnetic circuit such as a magnetic force line 8 is formed in the voice coil motor 5. At this time, since the sewing machine head frame 2 is formed of a ferromagnetic material, the magnetic resistance is small, so that the magnetic flux is not reduced. The sewing machine head frame 2 is a conventional voice coil motor (see FIG. 11). The same function as that of the machine frame 126 (see FIG. 11) is exhibited.

  The coil bobbin 54 is provided in close contact with the inner surface of the mounting hole 2 a of the voice coil motor 5 formed in the sewing machine head frame 2. The sewing machine head frame 2 has a through hole 2b that is continuous with the mounting hole 2a and penetrates from the front surface to the back surface of the sewing machine head frame 2, and the drive rod 4 is disposed in the through hole 2b. Thus, the drive rod 4 connects the thread tensioner 3 disposed on the front side of the sewing machine head frame 2 and the voice coil motor 5 disposed on the back side. In addition, a retaining ring 59 formed in a substantially C shape adjacent to one end of the coil bobbin 54 is attached in the vicinity of the opening of the mounting hole 2a, and the coil bobbin 54 is positioned. Here, the coil bobbin 54 around which the coil 55 is wound is not accommodated in the coil yoke, and is directly mounted in the mounting hole 2 a formed in the sewing machine head frame 2. That is, the sewing machine head frame 2 also functions as a coil yoke.

The other end of the drive rod 4 is formed of a non-magnetic material such as austenitic stainless steel, and is housed and fixed inside the coil bobbin 54 and provided with a bearing 56 that guides the movement of the drive rod 4 in the axial direction. ing. The bearing 56 is formed so as to be fitted into a fitting hole formed in the coil bobbin 54, and prevents the drive rod 4 from being displaced in the radial direction after the bearing 56 is attached.
At one end of the coil bobbin 54, a lead wire 58 electrically connected to the end of the winding of the coil 55 is drawn out and can be energized from the outside.

<Effect>
When the coil 55 is energized from the power source via the lead wire 58, the left hand of Fleming is affected by the influence of the current flowing in the coil 55 and the magnetic field of the permanent magnets 52 and 53 provided on the mover shaft 51, as shown in FIG. In accordance with the law, thrust is generated in the axial direction of the mover shaft 51 (the S direction in FIG. 6). When thrust is generated in the mover shaft 51, the mover shaft 51 moves along the axial direction (the S direction in FIG. 6) and is connected to the mover shaft 51 as the mover shaft 51 moves. The drive rod 4 also moves in the same direction as the mover shaft 51. When the drive rod 4 is moved, the positioning collar 35 connected to the drive rod 4 is moved. When the moving positioning collar 35 is in contact with the dish presser 33, the dish presser 33 is moved. By moving, one thread tension tray 31 is moved toward the other thread tension tray 32. By the movement of the thread tension tray 32, the thread tension tray 32 comes into contact with the thread tension tray 31, whereby the thread can be clamped. In addition, since the thrust generated in the axial direction of the mover shaft 51 is changed by changing the amount of current supplied to the coil 55, the pressure for holding the yarn between the pair of thread tension plates 31, 32 can be changed. During sewing, the thread tension desired by the user can be generated by adjusting the thread clamping force by the thread tension plates 31 and 32 when the thread is fed from the thread supply source.

Here, the voice coil motor 5 provided in the mounting hole 2a formed in the sewing machine head frame 2 has permanent magnets 52 and 53 arranged on the movable element 6 side and a coil 55 arranged on the stator 7 side. Therefore, even when the coil 55 is energized and thrust is generated, only the mover shaft 51 moves, and the coil 55 remains fixed to the coil bobbin 54, so that it is not disconnected.
Since the coil 55 on the stator 7 side is mounted on the mounting hole 2a while being wound around the coil bobbin 54 and is in contact with the sewing machine head frame 2, the heat generated by the coil 55 due to energization is generated by the coil 55 or Since it is transmitted directly from the coil bobbin 54 to the sewing machine head frame 2, the heat dissipation of the voice coil motor 5 can be improved.

  Further, since the drive rod 4 extends from the front side to the back side of the machine head frame 2 and is supported by the bearing 56 and the thread tension rod 37, the support interval is maintained even if the length of the drive rod 4 is shortened. Since it is not shortened so much and the influence of the axial misalignment is reduced, the coaxial accuracy is easily obtained, the gap between the permanent magnets 52 and 53 and the coil bobbin 54 can be reduced, and the thrust of the voice coil motor 5 is improved. be able to. Further, since the bearing 56 is fitted to the coil bobbin 54, the bearing 56 is not displaced in the radial direction of the mover shaft 51, and the tolerance at the time of attachment can be made relatively small. Further, the fitting portion from the drive rod 4 to the bearing 56 is reduced, the accumulated tolerance between the respective parts is reduced, the axial center accuracy of the drive rod 4 and the bearing 56 can be improved, and the bearing 56 is moved when the drive rod 4 is moved. And the hysteresis of the yarn tension can be reduced. Further, also in the management of the gap between the outer periphery of the permanent magnets 52 and 53 provided on the mover shaft 51 and the inner periphery of the coil bobbin 54, since the component via the drive rod 4 and the coil bobbin 54 is only the bearing 56, each component Therefore, the tolerance at the time of attachment can be made relatively small, and the influence of the accumulated tolerance in the voice coil motor 5 can be reduced.

  Further, since the voice coil motor 5 substitutes the sewing machine head frame 2 without providing a separate coil yoke, the coil 55 can be wound around the coil bobbin 54 by the thickness of the coil yoke. . Thereby, the thrust which can be output by the voice coil motor 5 can be increased. Therefore, when the voice coil motor 5 that outputs the same thrust is produced, the voice coil motor 5 of the present embodiment can be downsized. And weight reduction can be implement | achieved by achieving size reduction, and the responsiveness of the voice coil motor 5 can be improved. Furthermore, by reducing the size of the voice coil motor 5, it can be incorporated in the sewing machine head frame 2, and the sewing machine can be reduced in size. Further, since it is possible to omit measures to be taken when the voice coil motor 5 is provided outside the sewing machine (for example, installation of a protective cover for preventing an operator from touching the heated voice coil motor 5), Cost can be reduced.

Moreover, since the number of parts can be reduced by substituting the coil yoke with the sewing machine head frame 2, the cost for production of the voice coil motor 5 can be reduced.
In addition, the coil 55 generates heat when energized. However, since the coil yoke is not provided, heat is quickly transmitted to the sewing machine head frame 2, and the sewing machine head frame 2 is in contact with the outside air. The sewing machine head frame 2 can be cooled immediately. Thereby, the heat dissipation efficiency of the voice coil motor 5 can be improved.
Further, the voice coil motor 5 is provided in the sewing machine head frame 2, but by reducing the number of parts, it is possible to facilitate the work when the voice coil motor 5 is assembled to the sewing machine head frame 2. .
Further, the distance between the thread tensioner 3 and the voice coil motor 5 can be shortened, and the drive rod 4 connected thereto is supported by the bearing 56, so the load acting on the drive rod 4 is reduced. Accordingly, it is possible to prevent a decrease in responsiveness and a decrease in movement accuracy due to the bending or bending of the drive rod 4.

<Others>
The scope of the present invention is not limited to the above embodiment. For example, the coil bobbin 54 and the bearing 56 may be integrally formed. Thereby, the number of parts can be further reduced, and cost reduction and work can be facilitated. The number of permanent magnets 52 and 53 and the number of windings of the coil 55 are arbitrary and can be freely changed.
In addition, the design can be freely changed within the scope of the invention.

The figure which shows the state provided with the thread tension device in the sewing machine. (A) is a front view of a part of a sewing machine provided with a thread tension device, and (b) is a cross-sectional view taken along line AA of (a). The disassembled perspective view which shows a thread tension device. The disassembled perspective view which shows a voice coil motor. (A) is a shape of a permanent magnet, (b) is a figure which shows the magnetization direction of one permanent magnet, (c) is a figure which shows the magnetization direction of the other permanent magnet. Sectional drawing which shows the internal structure of a voice coil motor. The figure which shows the state provided with the thread tension device in the sewing machine in a prior art. The figure which shows the structure of the thread tension device in FIG. The figure which shows the thread tension apparatus in another prior art. Sectional drawing which shows the internal structure of the solenoid in FIG. Sectional drawing which shows the internal structure of the voice coil motor in a prior art.

Explanation of symbols

1 Thread tension device 2 Sewing machine head frame 31 Thread tension tray (one thread tension tray)
32 Thread tension dish (the other thread tension dish)
33 Dish presser 4 Drive rod (drive mechanism)
5 Voice coil motor (drive source)
52 Permanent magnet 53 Permanent magnet 6 Movable element 7 Stator

Claims (3)

A pair of thread tension plates for holding the thread, a plate presser that is movable in contact with one thread tension plate so that one thread tension plate is moved toward and away from the other thread tension plate, and one thread tension A drive mechanism for driving the plate press so that the plate approaches the other thread tension plate, a drive source provided in a sewing machine head frame made of a ferromagnetic material, and driving the drive mechanism; With
In the thread tension device of a sewing machine, the drive source includes a mover provided with a permanent magnet and a stator provided with a coil wound around the permanent magnet at a predetermined interval.
A thread tension device for a sewing machine, wherein the sewing machine head frame is a coil yoke of the coil.   The thread tension device for a sewing machine according to claim 1, wherein a bearing of the movable element is provided on a coil bobbin in which the coil is accommodated.   The thread tension device for a sewing machine according to claim 2, wherein the coil bobbin and the bearing are integrally formed.

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