JP2018175723A - Sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of thread cast-off and stitch skipping in an actuation cycle of a first stitch, in a sewing machine including a balance for capturing and pulling a needle thread by traversing the needle thread.SOLUTION: A balance 7 which a sewing machine 1 includes traverses a thread guide 4 of a needle thread 200 and captures and pulls the needle thread 200. This sewing machine 1 includes a shutter 820 having the thread guide 4 in a deep part and moving so as to be interposed in a groove path 41 in which the needle thread 200 is hooked. This shutter 820 is interposed in the groove path 41 when the needle thread 200 is hooked.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sewing machine provided with a balance that moves a yarn hooking portion across an upper yarn to capture and pull the upper yarn at the yarn hooking portion.

  The sewing machine forms a thread loop of the upper thread, and by inserting the lower thread through the upper thread thread ring, the upper thread and the lower thread are entangled to form a seam. The upper thread is inserted from the thread spool into the needle, and the lower thread is stored in a hook having a tip in a state of being wound around a bobbin. The thread ring is formed by raising the needle through which the upper thread is inserted from the bottom dead center. The hook tip of the hook captures the thread ring, and the hook rotates while capturing the thread ring, and the upper thread and the lower thread are entangled as the upper thread dives the bobbin. Here, as a preparatory step of the sewing operation, the operator sets the thread piece on the sewing machine and places the thread (upper thread) in the thread path including the insertion to the needle by hooking the upper thread (or It is called a yarn hook).

  In an apparatus called a horizontal balance, a yarn hooking portion moves forward across an upper yarn (see, for example, Patent Document 1 and Patent Document 2). The yarn hooking portion of the horizontal balance forms a hook shape, and captures the upper yarn in the forward path and pulls the upper yarn in a V-shape. The yarn hooking portion is separated from the upper yarn in the return path, whereby the upper yarn is uncaptured. By these operations, the upper thread necessary for stitch formation, including the thread ring, is loosened (supplied), and, if necessary, the looseness is recovered (pulled up).

  Conventionally, when the operation switch is turned off, the sewing machine stops the needle at the top dead center. When the needle is at the top dead center in the horizontal balance, the yarn hooking portion is stopped at a position halfway through the forward path after passing the upper thread from the forward start point. Therefore, when the upper thread is replaced while the operation switch is turned off, in the operation cycle of the first needle after the operation switch is turned on, the yarn hooking portion is from the middle of the forward path after passing the upper thread to the forward path end point I will head.

  When the yarn hooking portion operates from the middle of the forward pass after passing the upper thread, the yarn hooking portion can not cross the upper thread in the first forward pass, and can not catch and pull the upper thread in the first forward pass. If the upper thread is not caught and pulled, the upper thread is not loosened, the supply amount corresponding to the thread and ring is insufficient, and there is a possibility that the point of the sword can not capture the upper thread. That is, there is a possibility that so-called eye skipping can not be formed in the operation cycle of the first stitch where the seam can not be formed.

  Therefore, a sewing machine has been proposed that stops operation when the yarn hooking portion is positioned between the forward path starting point and the yarn path (see, for example, Patent Document 2). In this sewing machine, since the upper thread can be reliably captured and pulled from the operation cycle of the first stitch after replacing the upper thread, slack equivalent to the thread ring is generated in the upper thread and popping in the operation cycle of the first stitch is prevented Be done.

  However, the slack corresponding to the upper thread created in the first needle operation cycle may be supplied from the presser foot side and the upper thread tensioner side of the sewing machine. This is because there is no seam in the cloth and there is no stop in the supply from the side of the presser foot by the seam. How much is supplied from which side of the presser foot and the upper thread tensioner side depends on the balance of the upper thread holding force of the presser foot and the upper thread tensioner.

  The upper thread is pulled out from the bottom side of the presser foot by the user as preparation before sewing. The amount of pulling out is small, and when a large amount of upper thread is supplied from the presser foot side by the pulling of the thread engagement portion, the upper thread may be released from the needle or the cloth. There is a risk.

  In addition, the sewing machine is equipped with a toy car. Hashimi cars are used to raise and lower the needle manually. There is a common part between the mechanism for driving the needle and the mechanism for driving the yarn hooking portion, and the manual operation of the wheel also causes displacement of the yarn hooking portion. Therefore, even if the sewing machine is stopped when the yarn hooking part is positioned between the yarn path and the yarn path from the forward path, the yarn hooking part is moved to a position beyond the yarn road by manual operation of the wheel There is also.

  In the case where the handwheel is operated manually, the yarn hooking portion can not catch and pull the upper thread in the operation cycle of the first needle after all, and there is not enough room for loosening the upper thread, and the upper thread by the thread removing spring. By pulling up, the supply amount corresponding to the thread ring is insufficient, and the point of the sword can not catch the upper thread. That is, there is still the risk of skipping at the first eye operation cycle.

Unexamined-Japanese-Patent No. 2-111392 Unexamined-Japanese-Patent No. 2002-224481

  As described above, in a sewing machine provided with a balance that captures and pulls the upper thread across the upper thread, problems such as thread loss and jumps due to less loosening of the upper thread in the operation cycle of the first needle occur. The present invention has been proposed to solve the problems of the prior art as described above, and in a sewing machine provided with a balance that captures and pulls an upper thread across the upper thread, the thread is operated at the first operation cycle of the first stitch. The object is to prevent the occurrence of missing and popping.

  In order to achieve the above object, a sewing machine according to the present invention is a sewing machine in which an upper thread and a lower thread are entangled by a cooperative operation of a needle and a hook to form a seam. A balance which captures and pulls the upper thread in a crossing direction, has a thread path at a deep portion, and a groove path in which the upper thread can be hooked in and the groove path so as to be moveable to change the thread path A shutter is provided, wherein the shutter is interposed in the groove when the upper thread is engaged.

  The presser foot includes a presser foot for pressing an object to be sewn, and a presser lift lever for moving the presser foot up and down. The shutter is interlocked with the movement of the presser lift lever, and the shutter is operated while the presser foot is raised. The groove may be interposed.

  An upper thread tensioner for providing a tension pressure to the upper thread, the upper thread tensioner comprising: a movable plate and a fixed plate sandwiching the upper thread; and an actuator for moving the movable plate toward the fixed plate The shutter may be actuated by the actuator.

  A sensor may be provided to detect the engagement of the upper thread, and the shutter may intervene in and retract from the groove based on the result of detection by the sensor.

  The sensor for detecting the engagement of the upper thread may be a sensor for detecting the presence or absence of the upper thread provided on the thread path.

  The sensor that detects the engagement of the upper thread may be a sensor that detects the elevation of the press-up lever.

  The sensor that detects the engagement of the upper thread may be a sensor that detects the elevation of the presser foot.

  The above-mentioned putting in should just be what the above-mentioned upper thread is installed in the thread way of the above-mentioned upper thread.

  According to the present invention, since the upper thread can be loosened when the upper thread is put in, the possibility of the occurrence of thread loss and popping in the operation cycle of the first stitch after the upper thread replacement is reduced. .

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the whole sewing machine, (a) shows an external appearance, (b) shows the outline of an internal structure. It is a perspective view which shows the detailed structure of a balance. It is a figure which shows the movement locus | trajectory of a thread hook part. It is an exploded perspective view of an upper thread tensioner. It is a front perspective view of an upper thread tension device. It is a rear perspective view of the upper thread tensioner. It is a block diagram showing composition of a controller of a sewing machine. The state of the shutter in the timing which puts in an upper thread is shown, (a) is a top view of an upper thread tension device, (b) is an enlarged top view near a shutter. The shutter which retracted | saved is shown, (a) is a top view of an upper thread tension device, (b) is an enlarged top view of shutter vicinity. It is a schematic diagram which shows the state of the upper thread after shutter retraction | saving. It is a perspective view which shows the state of the balance after steering wheel operation. It is a side view which shows the state of the upper thread in the state which the thread removal spring jumped up. It is a perspective view which shows a pressing foot, (a) is a state in which the pressing foot was lowered, and (b) shows a state in which the pressing foot was raised. It is a top view which shows the other example of an upper thread tension device.

First Embodiment
(Overall configuration of sewing machine)
A sewing machine according to a first embodiment will be described in detail with reference to the drawings. The sewing machine 1 shown in FIG. 1 is a household, professional or industrial device for sewing the fabric 100, and drops the needle 3 against the fabric 100 placed on the needle plate 21, and the upper thread 200 and the lower thread Convolute with 300 to form a seam. The sewing machine 1 includes a needle bar 31 which supports the needle 3 at its tip and reciprocates with the needle 3, and a hook 5 having a sword tip on its outer periphery and rotating with the sword tip.

  The needle bar 31 extends perpendicularly to the needle plate 21 from the head portion 1 a of the sewing machine 1 and supports the needle 3 at the tip on the needle plate 21 side. The upper thread 200 is drawn out from the thread piece by the user, is engaged in the groove 41 formed in the head portion 1 a of the sewing machine 1, is inserted into the needle 3, and is further pulled out an arbitrary amount. Pass along. The groove bottom of the groove 41 is a yarn path 4 on which the upper thread tensioner 8 and the balance 7 provided in the sewing machine 1 operate.

  The kettle 5 has an internal hollow drum shape opened in one plane, is mounted horizontally or vertically with respect to the needle plate 21, and is rotatable in the circumferential direction. The hook 5 has a tip on its circumferential surface for capturing a thread ring, and accommodates therein a bobbin around which the lower thread 300 is wound.

  The needle bar 31 and the hook 5 are driven by the common sewing machine motor 6 as a power source via respective transmission mechanisms. An upper shaft 61 extending horizontally is connected to the needle bar 31 via a crank mechanism 62. When the crank mechanism 62 converts the rotation of the upper shaft 61 into linear motion and transmits it to the needle bar 31, the needle bar 31 moves up and down. In addition, the upper wheel 61 is attached with the wheel 65, and it is possible for the user to manually rotate the upper shaft 61 manually.

  The hook 5 is provided inside the bed 1 b of the sewing machine 1, and a horizontally extending lower shaft 63 is connected to the hook 5 via a gear mechanism 64. When the hook 5 is installed horizontally, the gear mechanism 64 is, for example, a cylindrical worm gear having an axial angle of 90 degrees. The gear mechanism 64 converts the rotation of the lower shaft 63 by 90 degrees and transmits it to the hook 5, whereby the hook 5 rotates horizontally.

  In such a sewing machine 1, the needle 3 penetrates the fabric 100 with the upper thread 200 by the reciprocating motion of the needle bar 31. When the needle 3 rises from the bottom dead center, the upper thread 200 forms a thread ring. The hook 5 rotates while capturing the thread ring with the point of a sword, and the bobbin from which the lower thread 300 is fed passes through the thread ring as the hook 5 rotates. At this time, the lower thread 300 also passes through the thread loop of the upper thread 200, and the upper thread 200 and the lower thread 300 are entangled and tightened to form a seam.

  The balance 7 and the upper thread tensioner 8 acting on the yarn path 4 deliver the upper thread 200, control the tension of the upper thread 200, loosen the upper thread 200, and further tighten the extended upper thread 200. Thereby, thread formation and thread tightening of the upper thread 200 are controlled.

(Balance)
The balance 7 shown in FIG. 2 is a device having a yarn hooking portion 71 crossing the yarn path 4 of the upper yarn 200, and repeating the catching, catching and releasing of the upper yarn 200 by the reciprocating motion of the yarn hooking portion 71. is there. The yarn hooking portion 71 crossing the yarn path 4 generally crosses the vertically extending section of the yarn path 4 horizontally, and the balance 7 having the yarn hooking portion 71 moving horizontally forward is called a horizontal balance.

  A gear mechanism 72 for horizontally moving the yarn hooking portion 71 is installed on the upper shaft 61. A cylindrical worm gear 72 a is formed on the circumferential surface of the upper shaft 61, and a cylindrical wheel 72 b having an axis perpendicular to the upper shaft 61 meshes with the cylindrical worm gear 72 a. A gear mechanism 72 is formed by the cylindrical worm gear 72a and the cylindrical wheel 72b. The gear mechanism 72 sets an axial angle to 90 degrees, and converts rotational movement on a vertical plane to rotational movement on a horizontal plane.

  The cylindrical wheel 72b doubles as a crankshaft. Connected to the cylindrical wheel 72b is a crank arm 73 formed of an egg-shaped plate. A part of the circumferential surface of the crank arm 73 bulges in the radial direction. A boomerang-shaped balance body 74 opened at an obtuse angle is connected to the bulging portion of the crank arm 73 via a crank pin. The balance body 74 has a yarn hooking portion 71 on the tip end side with the crank arm 73 side as a base end. A swing link 75 is connected to a bending point of the balance 74 via a crank pin. The swing link 75 is a fixed end whose one end is connected to a machine frame or the like.

  In addition, in the balance 74, the connection point with the crank arm 73 and the thread engagement portion 71 are different in height, and the balance 74 is bent in the boomerang shape along the horizontal surface and also twice in the height direction The step portion is provided by bending, and the connection point side and the yarn hooking portion 71 side extend at different heights.

  According to the balance 7, the yarn hooking portion 71 is regulated by the swing link 75, and reciprocates in a circular arc in the horizontal plane centering on the fixed end of the swing link 75. Further, when the balance 74 is restricted by the swing link 75 to change the direction, the yarn hooking portion 71 reciprocates in a circular arc in the horizontal plane centering on the connection point with the swing link 75. As shown in FIG. 3, the yarn hooking portion 71 follows different trajectories in the forward path 71a and the return path 71b by combining the two reciprocating movements. The yarn hooking portion 71 follows a locus expanded in an arc shape in the first half of the forward pass, and follows a locus drawn in an arc in the second half of the return path.

  As shown in FIGS. 2 and 3, the balance 7 is installed so that an arc-like locus drawn on the front half 71 a of the yarn hooking portion 71 intersects with the yarn path 4 of the upper yarn 200. Further, in the yarn hooking portion 71, the side facing the yarn path 4 from the forward path start end 71c has a hook shape. Therefore, the yarn hooking portion 71 traverses the yarn path 4 in the forward path 71a, captures the upper yarn 200 present in the yarn path 4 so as to hook it, and pulls the upper yarn 200 so as to scratch it by continuing the forward movement. Further, the yarn hooking portion 71 separates from the upper yarn 200 in the return path 71b to release the upper yarn 200 from the catching state, and avoids the yarn path 4 to return to the return path end, that is, the forward path start end 71c.

(Upper thread tensioner)
FIG. 4 is an exploded view of the upper thread tensioner 8, and FIG. 5 is a front perspective view of the upper thread tensioner 8. As shown in FIGS. 4 and 5, the upper thread tensioner 8 is provided with a fixed plate 801 and a movable plate 802 face to face. The fixed plate 801 and the movable plate 802 are disposed so as to sandwich the thread path 4 of the upper thread 200 therebetween. The movable plate 802 is freely penetrated by the shaft 803 leading to the fixed plate 801, and is slidable in a direction in which the fixed plate 801 contacts and separates. When the movable plate 802 contacts the fixed plate 801, the upper thread 200 passing through the yarn path 4 is sandwiched between the fixed plate 801 and the movable plate 802, and the upper thread 200 receives a pressing force. This pressing force is the pressure on the upper thread 200. The upper thread 200 receives a tension pressure corresponding to the adhesion strength of the movable plate 802 to the fixed plate 801.

  Hereinafter, the direction in which the fixed plate 801 and the movable plate 802 contact and separate is referred to as the plate contact and separation direction, in particular, the direction in which the movable plate 802 contacts the fixed plate 801 is the plate contact direction, and the direction in which the movable plate 802 separates from the fixed plate 801 It is called the tray separation direction. In addition, the direction along the horizontal plane where the upper shaft 61 extends is orthogonal to the plate contact / separation direction, and is referred to as the front and back direction, in particular, the direction from the yarn path 4 to the inlet of the groove 41 is the forward direction, The direction toward the deep yarn path 4 is called the back direction.

  The upper thread tensioner 8 is provided with a pusher 804 for pushing the movable plate 802 toward the fixed plate 801 on the back side of the movable plate 802, that is, on the side opposite to the surface facing the fixed plate 801. The pusher 804 is provided with a plurality of projections on the movable plate 802 side, and can be pushed out by uniformly applying a force to the entire movable plate 802. A compression spring 807 is provided on the back side of the pusher 804, that is, on the side opposite to the side facing the movable plate 802. The pusher 804 and the compression spring 807 are inserted into the shaft 803, and the compression spring 807 extends in the disc contact / separation direction. The tip of the compression spring 807 is connected to the back surface of the pusher 804.

  The biasing force of the compression spring 807 pushes the movable plate 802 into the fixed plate 801 via the pusher 804, and a pressure corresponding to the amount of contraction of the compression spring 807 is applied between the movable plate 802 and the fixed plate 801. The upper thread tensioner 8 is provided with a tone setting rod 808 that causes the compression spring 807 to contract.

  The tension setting rod 808 is located on the opposite side of the compression spring 807 to the pusher 804. The pressure setting rod 808 is integrally provided with a pressing plate 808a loosely inserted in the shaft 803 and a pin body 808b extending in the front-rear direction orthogonal to the dish contact / separation direction. The pressing plate 808 a has a disk surface that is the same as or slightly larger than the outer diameter of the compression spring 807, and a cylindrical body that bulges from the center of the disk surface and fits into the compression spring 807. .

  The pin body 808 b is loosely inserted in the long hole 809 elongated in the dish contact / separation direction, and the tone setting rod 808 is guided by the long hole 809 and moves in parallel in the disc contact / separation direction. The tension setting rod 808 translates in the dish contact direction to contract the compression spring 807 using the pressing plate 808a. The amount of contraction of the compression spring 807 is determined by the amount of movement of the tone setting rod 808.

  The upper thread tensioner 8 includes a rotary motor 810 and a gear 811 for translating the tension setting rod 808 in parallel. The rotary motor 810 is a stepping motor or a servomotor. The rotary shaft of the rotary motor 810 and the gear 811 are meshed directly or through another gear. The flat surface of the gear 811 and the pin body 808 b of the tone setting rod 808 are orthogonal to each other.

  On the first flat surface 812 of the gear 811, a spiral groove 813 is formed which gradually spreads while drawing a spiral from the rotation center of the gear 811 to the outer periphery. The pin body 808 b of the tone setting rod 808 is fitted in the spiral groove 813. The gear 811 is a cam, and the tone setting rod 808 is a cam follower. When the gear 811 rotates, the tension setting rod 808 is pushed from the center side of the gear 811 to the outer peripheral side while being restricted by the elongated hole 809, and contracts the compression spring 807 in the disc contact direction. That is, the pressure of the upper thread 200 is controlled in accordance with the amount of rotation of the motor 806.

(String take-off spring)
As shown in FIGS. 4 and 5, a thread taker spring 816 is attached to the upper thread tensioner 8. The thread take-up spring 816 increases the path length of the thread path 4 in response to the slack generated in the upper thread 200, and absorbs the slack of the upper thread 200 with the increased path length. The thread take-up spring 816 is a metal wire torsion spring, and has a coil portion 817 and an arm 818. The arm 818 is protruded and extended in a direction orthogonal to the winding axis of the coil portion 817, and is subjected to several bending processes along the way.

  The coil portion 817 is inserted into the shaft 803 and is located on the opposite side of the pair of the fixed plate 801 and the movable plate 802 from the compression spring 807. As an example of the present upper thread tensioner 8, the coil portion 817 is adjacent to a pair of the fixed plate 801 and the movable plate 802 across the machine frame.

  The arm 818 extends in the plate separating direction while rotating in a circular manner, passes the row of the fixed plate 801 and the movable plate 802, and spans the tip of the arm 818 on the shaft 803. The arm 818 is bent at an angle of 90 degrees with an imaginary line crossing both straight arm portions of the U straightly in a straight line, and when viewed from the direction along the winding axis of the coil portion 817, it is L-shaped or V-shaped Make up The bending direction of the arm 818 coincides with the winding direction of the coil portion 817.

  In the thread take-up spring 816, the U-shaped curved portion of the arm 818 functions as a thread guide portion 819. The upper thread 200 is hung on the thread guiding portion 819 by the user, and the coil guiding portion 819 is biased by the coil portion 817 so as to jump up in an arc shape. The yarn guiding portion 819 is biased by the tightened upper yarn 200 and pushed down along the yarn path 4 formed by the tightened upper yarn 200. On the other hand, when slack occurs in the upper thread 200, the yarn guide portion 819 jumps up in an arc while hooking the upper thread 200 by the biasing force accumulated by the coil portion 817, and bends the thread path 4 formed by the upper thread 200. In other words, the path length of the yarn path 4 is increased, and the slack of the upper yarn 200 is absorbed by the yarn path 4.

  In addition, when the upper thread 200 is hooked to the thread path 4, the upper thread 200 is hooked to the sewing machine 1 so as to be in contact with the thread guide portion 819. At this time, the arm 818 is bent in a V-shape, so that a receiving port with the thread guiding portion 819 placed on the front side is formed on the hooking side of the upper thread 200. Guidelines will be formed on both sides to prevent removal of the upper thread 200.

(shutter)
As shown in FIGS. 4 and 5, the upper thread tensioner 8 is provided with a shutter 820. The shutter 820 intervenes in the groove 41 at the time of installation or replacement of the upper thread 200, that is, when the yarn is hooked, and blocks between the inlet of the groove 41 and the yarn path 4. In addition, the shutter 820 retracts from the groove 41 after the upper thread 200 is engaged. As a result, when replacing the upper thread 200, the upper thread 200 has slack without being along the thread path 4. The shutter 820 is a barrier plate extending to one end of the crank lever 821 and located beside the channel 41.

  The shutter 820 rotates in an arc around the crank pin 825 of the crank lever 821 to intervene in the groove 41. The crank lever 821 integrally has a base bar 822, a short bar 823 bent and extended from one end of the base bar 822, and an elongated bar 824 bent and extended from the other end of the base bar 822. The ends are substantially U-shaped bent in the same direction. In the present embodiment, the long bar 824 is formed separately from the base bar 822 and is fastened to the base bar 822 by a screw or the like.

  The short bar 823 has its end in contact with the second flat surface 814 (see FIG. 6) of the gear 811. The second flat portion 814 is the opposite surface of the first flat portion 812 in which the spiral groove 813 is formed. The base bar 822 extends from the gear 811 in the dish contact direction until it passes through the row of the compression spring 807, the movable plate 802 and the fixed plate 801, and the approximately central portion is pivotally supported by the crank pin 825 There is.

  The long bar 824 passes the yarn path 4 through the side of the pair of the movable tray 802 and the fixed tray 801 and extends to the side of the inlet of the channel 41. The tip of the long bar 824 is bent and extended toward the channel 41, and the extended portion is a shutter 820. The long bar 824 is bent obliquely to the sewing machine bed side in order to cause the shutter 820 to intervene in the groove 41 on the needle 3 side with respect to the thread take-up spring 816.

  As shown in FIG. 6, the second flat surface 814 is formed with a trapezoidal bulging portion 815 extending in a certain angular range of the gear 811. The formation position of the bulging portion 815 is on the movement locus drawn by the short bar 823 of the crank lever 821 on the second flat surface 814. When the gear 811 is rotated by the rotation motor 810 and the bulging portion 815 and the short bar 823 of the crank lever 821 match, the short bar 823 is pushed up and the long bar 824 approaches the groove 41 centering on the crank pin 825 To rotate. Thus, the shutter 820 provided at the end of the long bar 824 intervenes in the groove 41.

  Conversely, when the gear 811 is reversely rotated by the rotary motor 810 and the bulging portion 815 and the short bar 823 of the crank lever 821 do not match, the short bar 823 is lowered to the second flat surface 814 and the long bar 824 is cranked. It is pivoted back around the pin 825 away from the channel 41. Thus, the shutter 820 provided at the end of the long bar 824 retracts from the groove 41.

  The position where the bulging portion 815 is formed is where the short bar 823 of the crank lever 821 ascends the bulging portion 815 when the tone setting rod 808 is positioned at the center or the outermost portion of the spiral groove 813. That is, when the upper thread tensioner 8 applies pressure to the upper thread 200, the shutter 820 does not intervene in the groove 41.

(controller)
FIG. 7 is a block diagram showing the configuration of the controller 9 of the sewing machine 1. As shown in FIG. 7, the sewing machine 1 incorporates a controller 9 for controlling the sewing machine motor 6 and the upper thread tensioner 8 and the like. The controller 9 is configured by a so-called computer or microcomputer and peripheral devices. The computer or microcomputer includes an arithmetic and control unit also called a CPU, a memory called a ROM called a program and data stored therein, and a work memory also called a RAM. The peripheral device includes a motor driver such as the sewing machine motor 6 and the upper thread tensioner 8 and an operation unit 94 serving as an input unit of the user. The operation unit 94 is a touch panel, a dial, a foot controller or the like.

  The controller 9 includes a drive control unit 91 mainly made up of at least an arithmetic control unit and a motor driver by execution of a program, a tone control unit 92, and a shutter control unit 93. When the stop operation is input to the operation unit 94, the drive control unit 91 stops outputting the drive signal to the sewing machine motor 6 at a predetermined timing. The output stop timing of the drive signal is when the yarn hooking portion 71 of the balance 7 is positioned at the forward path start end.

  The tone control unit 92 controls the upper thread tensioner 8. Specifically, the amount of rotation of the rotary motor 810 is controlled. The tension control unit 92 rotates the rotary motor 810 according to the upper thread tension information to clamp the upper thread 200 between the fixed plate 801 and the movable plate 802, and applies a pressing force to the upper thread 200. The upper thread tension information is content for determining the tension to the upper thread 200 input to the operation unit 94, and selection of texture etc., or sewing pattern, cloth feed amount, cloth thickness, sewing speed, needle amplitude It is sewing condition such as.

  The shutter control unit 93 drives the rotary motor 810 until the shutter 820 intervenes in the groove 41 and prevents the upper thread 200 from being engaged so as to reach the yarn path 4. The drive timing of the rotary motor 810 is when the upper thread 200 is replaced. For example, a proximity sensor (not shown) for detecting the hooking of the upper thread 200 into the thread path 4 is installed at the entrance of the channel 41. When the upper thread 200 is installed in the thread path 4, the upper thread 200 is detected by the proximity sensor. On the other hand, if the upper thread 200 is removed from the thread path 4 due to thread breakage or thread replacement, the proximity sensor upper thread 200 can not be detected. Then, the shutter control unit 93 drives the rotation motor 810 so that the short bar 823 of the crank lever 821 ascends the bulging portion 815.

(Action)
As shown in FIG. 8, when replacing the upper thread 200, the shutter control unit 93 moves the shutter 820 between the inlet of the groove 41 and the thread path 4 before the upper thread 200 is engaged. deep. That is, the rotary motor 810 is driven to bring the bulging portion 815 and the short bar 823 of the crank lever 821 into alignment. As the short bar 823 is pushed up, the crank lever 821 pivots about the crank pin 825, the long bar 824 approaches the groove 41, and the shutter 820 provided at the tip of the long bar 824 is the groove 41. Intervene inside.

  When the upper thread 200 is engaged while the shutter 820 intervenes in the groove 41, the upper thread 200 can not reach the thread path 4 and is caught on the shutter 820. At this time, the path length of the upper thread 200 is longer than the path length L along the thread path 4 by ΔL.

  Next, as shown in FIG. 9, the tension control unit 92 causes the balance 7 to pull the upper thread 200 in the operation cycle of the first stitch, that is, before the drive control unit 91 drives the sewing machine motor 6. The rotary motor 810 is rotated in accordance with upper thread tension information, and pressure is applied to the upper thread 200 by the movable plate 802 and the fixed plate 801. The operation cycle of the first stitch is the first operation cycle after the proximity sensor detects the engagement of the upper thread 200, and after the upper thread 200 is installed or replaced, or sewing including a thread cutting operation After interruption, it is the first needle reciprocation in the stitch forming operation.

  At this time, the short length bar 823 of the crank lever 821 is lowered from the bulging portion 815 by the pressure control unit 92, and the shutter 820 is retracted from the groove 41. Then, as shown in FIG. 10, the upper thread 200 which has been extended to the path length passing through the shutter 820 is loosened by the passing length ΔL even when it enters the thread path 4.

  As shown in FIG. 10, when the drive control unit 91 drives the sewing machine motor 6 and the balance 7 catches and pulls the upper thread 200 by the thread engagement portion 71, the shutter 820 sets a part of the pulling amount Lmax. It is scooped up by the looseness that has been caused to 200. Therefore, the yarn amount of the upper yarn 200 supplied from the presser foot 22 side by pulling by the balance 7 is reduced to Lmax-ΔL at the maximum, and so-called yarn missing in the first needle operation cycle after replacement of the upper yarn 200 Is suppressed.

  In addition, when the hammer wheel 65 is operated while the sewing machine 1 is stopped, as shown in FIG. 11, the yarn hooking portion 71 may be stopped by passing the yarn path 4 from the forward movement start end. When the upper thread 200 is replaced in this state, the yarn hooking portion 71 can not catch and pull the upper thread 200 in the first needle operation cycle. Therefore, the thread and ring portion of the upper thread 200 is not created by the balance 7.

  However, as shown in FIG. 12, immediately after the upper thread 200 is replaced, the shutter 820 loosens by ΔL ′ more than the path length L ′ when the thread take-up spring 816 pulls the upper thread 200. Therefore, even if the yarn hooking portion 71 can not capture and pull the upper yarn 200 in the operation cycle of the first stitch, and the yarn take-off spring 816 further pulls the upper yarn 200, the upper yarn 200 has a length ΔL ' Therefore, the possibility of so-called eye popping is reduced.

(effect)
Thus, the balance 7 provided in the sewing machine 1 captures and pulls the upper thread 200 across the thread path 4 of the upper thread 200. Such a sewing machine 1 has a shutter 820 which has a yarn path 4 at the deep portion and moves so as to be able to intervene in the groove 41 into which the upper thread 200 can be inserted to change the yarn path 4. It was made to intervene in channel 41 at the time of putting in of upper thread 200.

  As a result, when the upper thread 200 is hooked in, the upper thread 200 does not reach the thread path 4 and is caught on the shutter 820, and the path length is increased as compared with the state along the thread path 4. Therefore, when the shutter 820 retracts from the groove 41, the upper thread 200 is loosened. Therefore, in the operation cycle of the first needle after replacement of the upper thread 200, the amount of threads for forming the thread and ring of the upper thread 200 does not run short, and so-called popping and threading out are prevented.

  Further, the shutter 820 is attached to the upper thread tensioner 8. That is, the shutter 820 is operated by an actuator that moves the movable plate 802 toward the fixed plate 801. As a result, the same actuator can perform the pressure control and the loose production at the time of replacing the upper thread 200, and the cost of the sewing machine 1 can be reduced by reducing the number of parts.

  The sewing machine 1 only needs to have a mechanism by which the shutter 820 can intervene and retract in the groove 41, and the operating mechanism may adopt any of known configurations. For example, in addition to the rotary motor 810, a shutter 820 may be provided at the end of an actuator that generates a linear motion such as a solenoid or a voice coil motor, and the solenoid or voice coil motor may be controlled by the controller 9.

Second Embodiment
A sewing machine 1 according to a second embodiment will be described in detail with reference to the drawings. The same components and functions as those of the first embodiment are designated by the same reference numerals and their detailed description will be omitted.

  As shown in (a) and (b) of FIG. 13, the presser foot 22 of the sewing machine 1 can move up and down in the direction in which it is separated from the fabric 100. The presser foot 22 releases the cloth 100 and the upper thread 200 which are pinched by the needle plate 21 and the presser foot 22 by raising. Therefore, the fabric 100 and the upper thread 200 can be replaced while the presser foot 22 is in the raised state.

  Such a presser foot 22 is detachably attached to the tip of the presser bar 221. The sole of the presser foot 22 faces the needle plate 2 through the cloth 100. The presser bar 221 is mounted on the sewing machine frame, extends vertically toward the needle plate 2, and can be lifted and lowered in the axial direction of the bar. The presser foot 22 releases the fabric 100 and the upper thread 200 by the ascent of the presser bar 221, and the presser foot 22 presses the fabric 100 and the upper thread 200 as the presser bar 221 descends.

  Here, a presser bar holding member 222 is fixed to the presser bar 221. The presser bar 221 moves up and down in response to the displacement of the presser bar holder 222. The pressing rod holder 222 is configured of a flat plate 222a attached and fixed to the pressing rod 221, and an elevation lever 222b extending from the flat plate 222a.

  The flat plate 222a spreads perpendicularly to the axis of the pressing rod 221, and is fixed to the inserted pressing rod 221 by tightening or the like. From the viewpoint of strength, a reinforcing plate is extended on the flat plate 222a, and a U-shape including the flat plate 222a is formed. The lifting lever 222b is extended from the flat plate 222a. The lift lever 222b extends in a direction perpendicular or obliquely to the axis of the pressing rod 221.

  A compression spring 223 is installed on the upper surface of the flat plate 222a, in other words, the surface opposite to the surface on the side of the presser foot 22. The compression spring 233 is coaxial with the pressing rod 221 and has one end lowered to the flat plate 222a, and the other end is a fixed end fixed to the sewing machine frame. The distance between the fixed end and the flat plate 222 a is shorter than the free length of the compression spring 223. That is, the compression spring 223 is shrunk and inserted into the presser bar 221 to always bias the presser bar holder 222 in the downward direction.

  When the lifting lever 222b of the pressing rod holding member 222 is pushed up, the pressing rod 221 to which the holding rod holding member 222 is fixed rises against the urging force of the compression spring 223, and is lowered by the urging force of the compression spring 223 when the raising and lowering lever 222b is lowered. The rod 221 descends.

  The lifting lever 222 b is supported by the pressing and lifting lever 224 from below. The pressure raising lever 224 is a long rod pivotally supported by a pin so as to be rotatable, and a first cam body 224a, a second cam body 224b, and a grip portion 224c are formed in each portion. The first cam body 224a is a plate cam which extends around the rotation axis and whose side surface around the rotation axis is a cam surface. The second cam body 224b is a plate cam that is parallel to the first cam body 224a in the thickness direction and has a side surface around the rotation axis as a cam surface. The grip portion 224c is a rod extending from a base on which the first cam body 224a and the second cam body 224b are formed.

  That is, the first cam body 224a is a plate expanded along the axis of the pressing rod 221, and the pin is loosely inserted so as to penetrate the plate plane, and the rotation is orthogonal to the extension direction of the pressing rod 221 and the elevation lever 222b. Have an axis. The first cam body 224a is disposed below the pressing lever 22b with respect to the lifting lever 222b, and the lifting lever 222b is mounted on the upper side surface. The upper side surface connects the flat surface and the inclined surface, and the tip of the lift lever 222b extends to the inclined surface. This inclined surface is raised by the lift lever 222b.

  The grip portion 224 c is extended from the side surface of the first cam body 224 a, is exposed to the outside of the sewing machine 1, and can be gripped by the user. When the grip portion 224c is turned in such a direction that the inclined surface becomes steep, the lift lever 222b is lifted by the first cam body 224a, whereby the presser bar 221 and the presser foot 22 are raised.

  The second cam body 224b has a substantially egg-shaped plate shape, and is aligned with the first cam body 224a. In other words, the thickness range of half of the side surfaces of the press-up lever 224 is the first cam body 224a, and the thickness range of the other half is the second cam body 224b. The thread loosening lever 225 is in contact with the cam surface of the second cam body 224b. The thread release lever 225 is a substantially linear bar.

  A central portion of the thread release lever 225 is rotatably supported by a pin. One end side of the pin extends toward the second cam body 224b, and is in contact with the second cam body 222b from the pressing rod 221 side. Therefore, the output end 225b of the thread loosening lever 225 falls in the direction away from the pressing rod 221 by the rotation of the grip portion 224c.

  As shown in FIG. 14, an input bar 826 intervenes in a locus Tr in which the thread loosening lever 225 pivots when the user rotates the grip portion 224 c. The input bar 826 is extended from the crank lever 821 of the upper thread tensioner 8. That is, when the user rotates the grip portion 224 c and the thread loosening lever 225 is pushed down in the direction of displacing the input bar 826, the shutter 820 rotates.

  The input bar 826 extends from the base bar 822. More specifically, it extends from between the short bar 823 and the long bar 824, and when viewed from the short bar 823, the short bar 823 exists in the lifting direction when climbing the bulging portion 815. The output end 225 b of the thread release lever 225 is located between the short bar 823 and the input bar 826 and moves in the direction from the input bar 826 toward the long bar 824 when it falls down by the user operation.

  Therefore, when the output end 225 b of the thread loosening lever 225 falls down by the user operation, the output end 225 b pushes the input bar 826 toward the long bar 824, and the long bar 824 rotates so as to escape from the input bar 826. The shutter 820 intervenes in the channel 41.

  As described above, the sewing machine 1 according to the present embodiment includes the press-up lever 224 for moving the press-down foot 22 up and down. By interlocking the movement of the press-up lever 224 with the movement of the shutter 820, the press-up foot 22 operates. While ascending, the shutter 820 is interposed in the groove 41.

  The threading of the upper thread 200 is performed with the presser foot 22 raised. That is, the raising of the presser foot 22 is a signal that the upper thread 200 is engaged. Accordingly, when the shutter 820 is interposed in the groove 41 when the presser foot 22 is raised, the upper thread 200 is hooked on the shutter 820 without reaching the yarn path 4. Therefore, in the operation cycle of the first needle after replacement of the upper thread 200, the amount of threads for forming the thread and ring of the upper thread 200 does not run short, and so-called popping and threading out are prevented.

  By the way, in this sewing machine 1, needless to say, the movement mechanism of the shutter 820 by the rotation motor 810 described in the first embodiment and the movement of the shutter 820 interlocked with the movement of the pressing lever 224 described in the second embodiment. It is also possible to mount both mechanisms. Therefore, the moving mechanism of the shutter 820 by the rotary motor 810 and the moving mechanism of the shutter 820 by the push-up lever 224 described in the second embodiment are provided with a separation mechanism so that each operation is not affected by the other operation. ing. For example, when the shutter 820 is operated to be able to intervene in the groove by the rotary motor 810, the crank lever 821 pivots about the crank pin by the contact of the bulging portion 815 and the short bar 323, and the shutter 820 is in the groove. 41 intervenes. At the same time, the input bar 826 is also moved in the tray separation direction. That is, since the input bar 826 and the output end 225 b of the thread release lever 225 are separated, the operation of the shutter 820 by the rotary motor 810 does not affect the operation of the press-up lever 224.

  Conversely, when the crank lever 821 is rotated in conjunction with the operation of the press-up lever 224 as described above in a state where the shutter 820 is not capable of being interposed by the rotary motor 810, the short bar 823 has the gear 811 Therefore, the rotation of the crank lever 821 does not affect the gear 811.

  This means that the shutter drive mechanism interlocked with the movement of the press-up lever 224 and the shutter drive mechanism by the rotation motor 810 can be provided side by side. In particular, the shutter drive mechanism interlocked with the movement of the press-up lever 224 functions properly even when the power of the main body of the sewing machine 1 is not turned on. Depending on the state of the sewing machine 1, the operator can selectively use them, and reliable threading is possible.

(Modification)
In the second embodiment, the lifting of the presser foot 22 and the movement of the shutter 820 are mechanically interlocked. Not limited to this, a sensor for detecting the elevation of the presser foot 22, the presser bar 221 or the presser-lifting lever 224 is installed, the sensor and the controller 9 are connected by a signal line, and a detection signal of the sensor is input to the controller 9. Alternatively, the shutter control unit 93 may drive the rotary motor 810 of the upper thread tensioner 8.

  Examples of the sensor include a proximity sensor which is disposed in the vicinity of the presser foot 22, the presser bar 221 or the presser lift lever 224 and detects the approach or separation of the presser foot 22, the presser bar 221 or the presser lift lever 224. It is not restricted to this.

(Other embodiments)
Although the embodiments of the present invention have been described as above, various omissions, replacements, and changes can be made without departing from the scope of the invention. And this embodiment and its modification are included in the range and the gist of invention, and are included in the invention indicated to the claim, and its equivalent range.

Reference Signs List 1 sewing machine 21 needle plate 22 pressing foot 221 pressing bar 222 pressing bar holding member 222a flat plate 222b lifting lever 223 compression spring 224 pressing lift lever 224a first cam body 224b second cam body 224c grip portion 225 thread loosening lever 225b output end 3 needle Reference Signs List 31 needle bar 4 thread path 41 thread path 5 hook 6 sewing machine motor 61 upper shaft 62 crank mechanism 63 lower shaft 64 gear mechanism 65 hammer 7 balance 71 thread engagement portion 72 gear mechanism 72a cylindrical worm gear 72b cylindrical wheel 73 crank arm 74 balance body 75 Swing link 8 Upper thread tension device 801 Fixed plate 802 Movable plate 803 Shaft 804 Pusher 807 Compression spring 808 Condition setting rod 809 Long hole 810 Rotation motor 811 Gear 812 First flat surface 813 Spiral groove 814 Second flat surface 815 Expansion Part 816 Thread spring 817 Coil part 818 Arm 819 Thread guide part 820 Shutter 821 Crank lever 822 Base bar 823 Short bar 824 Long bar 825 Crank pin 826 Input bar 9 Controller 91 Drive control part 92 Condition control part 93 Shutter control part 94 Operation part 100 Fabric 200 Top Thread 300 Lower thread

Claims (8)

A sewing machine which entangles an upper thread and a lower thread by cooperative operation of a needle and a hook to form a seam,
A balance that captures and pulls the upper thread across the upper thread yarn path;
A groove having the yarn path at a deep portion and into which the upper yarn can be inserted;
A shutter that moves so as to be able to intervene in the groove and changes the yarn path;
Equipped with
The shutter is interposed in the groove when the upper thread is engaged;
A sewing machine characterized by A presser foot for pressing an object to be sewn;
A press-up lever that raises and lowers the presser foot;
Equipped with
The shutter is interlocked with the movement of the press-up lever, and the shutter is interposed in the groove while the presser foot is moving up.
The sewing machine according to claim 1, characterized in that Equipped with an upper thread tensioner to apply pressure to the upper thread,
The upper thread tensioner is
A movable plate and a fixed plate sandwiching the upper thread;
An actuator for moving the movable plate toward the fixed plate;
Equipped with
The shutter is actuated by the actuator;
The sewing machine according to claim 1 or 2, characterized in that A sensor for detecting the hooking of the upper thread;
The shutter may intervene in and retract from the groove based on a result detected by the sensor.
The sewing machine according to claim 1 or 3, characterized in that The sensor for detecting the engagement of the upper thread is:
A sensor for detecting the presence or absence of the upper thread provided on the thread path;
The sewing machine according to claim 4, wherein It has a sensor that detects the elevation of the pressing lever.
The shutter may intervene in and retract from the groove based on a result detected by the sensor.
The sewing machine according to claim 2, wherein A sensor for detecting the elevation of the presser foot;
The shutter may intervene in and retract from the groove based on a result detected by the sensor.
The sewing machine according to claim 2, characterized in that In the putting-in, the upper thread is installed in the thread path of the upper thread,
The sewing machine according to any one of claims 1 to 5, characterized by

Images