Sewing machine

Abstract

The present invention is provided with: a needle that holds a needle thread and moves up and down through a needle plate; a looper that holds a looper thread and reciprocates in a space below the needle plate to wind the looper thread around the needle thread; a retainer which reciprocates in a space below the needle plate and captures the looper thread; and a holder movement mechanism that changes the movement state of the holder while transmitting a driving force from a driving source to the holder. The retainer movement mechanism causes the retainer to reciprocate at a position within a certain range in a space below the needle plate and at a lower speed than the front and back of the retainer for a certain time, thereby continuing the state in which the retainer catches the looper thread.

Description

[0001] Cross-references of related applications

[0002] This application claims the priority based on Japanese Patent Application No. 2022-125579 and Japanese Patent Application No. 2022-188995, and incorporates the description of the present application specification by reference. Technical Field

[0003] The present invention relates to a sewing machine which can form a loop-shaped stitch with an enlarged looper thread without using a retainer needle penetrating a cloth. Background Art

[0004] In the past, there was a sewing machine that can form a loop-shaped stitch with an enlarged loop of the looper thread. For example, the sewing machine described in Japanese Patent Publication No. 2001-314681 (Patent Document 1). The sewing machine described in Patent Document 1 is configured as follows: a retainer that does not penetrate the needle plate and moves is provided below the needle plate, and the looper thread is retained by the retainer, thereby being able to form a loop-shaped stitch with an enlarged loop of the looper thread at the double chain link portion without using a retainer needle that penetrates the fabric to make a hole. According to the illustration of Patent Document 1, the loop-shaped stitch of the looper thread is enlarged at the double chain link portion. Figure 3 The stitches shown are equivalent to the stitches shown in FIG. 4 of Patent Document 1 (stitches observed from the back side of the fabric) (except that Figure 3 As shown, there will be no holes caused by the retainer needle penetrating the fabric).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2001-314681 Summary of the invention

[0009] Technical problem that the invention aims to solve

[0010] In the sewing machine described in Patent Document 1, the retainer is configured to receive the driving force of the main shaft provided inside and reciprocate along an arc-shaped track within a predetermined range (see Patent Document 1). Figure 2). Since the reciprocating movement is a simple reciprocating movement, when turning back during the reciprocating movement, the moving speed of the retainer will instantly become 0 as the moving direction changes, but the moving speed of the retainer in the outward movement and the return movement will change along a sine curve of a certain shape according to its relationship with time. Therefore, for example, in order to form a desired extended annular trace of the bend needle thread, it is necessary to extend the time that the retainer continuously holds the bend needle thread (the time from capturing the bend needle thread to releasing it). For this reason, in order to make the retainer move at a speed along the sine curve and hold the bend needle thread at the same time, the reciprocating movement stroke (reciprocating movement range) of the retainer needs to be set larger in accordance with the extended holding time. This is because after capturing the bend needle thread, the retainer moves to the turning point, and after the moving direction is reversed, the retainer releases the bend needle thread. However, for example in a small sewing machine, there is a limit to the expansion of the internal volume of the cylinder. Therefore, even if the retainer holds the needle thread only for the amount of time required to achieve the desired stitch, due to space constraints, the reciprocating range of the retainer cannot be accommodated within the cylinder, and the reciprocating stroke cannot be increased.

[0011] Therefore, the technical problem of the present invention is to provide a sewing machine that can extend the time the retainer retains the looper thread even if the reciprocating stroke of the retainer is not set to be large, and can achieve the desired extended stitch of the looper thread.

[0012] Solutions for solving technical problems

[0013] The present invention is a sewing machine comprising: a needle, which holds a needle thread and passes through a needle plate to move up and down; a curved needle, which holds the curved needle thread and reciprocates in the space below the needle plate so that the curved needle thread is wound around the needle thread; a retainer, which reciprocates in the space below the needle plate and captures the curved needle thread; and a retainer movement mechanism, which changes the movement state of the retainer while transmitting the driving force from a driving source to the retainer, and the retainer movement mechanism causes the retainer to perform the reciprocating movement at a position within a certain range in the space below the needle plate and at a certain time at a lower speed than before and after, thereby maintaining the state in which the retainer captures the curved needle thread.

[0014] Furthermore, it is possible to construct the certain range involved in the low-speed movement of the retainer by the retainer movement mechanism to be: the range between a turning position where the retainer reverses from the forward direction to the backward direction, and a position near the turning position and away from the turning position in the backward direction.

[0015] Furthermore, the retainer moving mechanism may be configured such that the retainer is retracted once from the return position within the certain range, and then is advanced again to the return position, and then is retracted again.

[0016] Furthermore, it is possible to construct the retainer movement mechanism to include a connecting rod mechanism, which is composed of two connecting rod units, and the connecting rod mechanism is constructed such that: through reciprocating input, the straight line connecting the input side connecting point and the output side connecting point of each of the two connecting rod units repeatedly changes between a part or all of a straight line state arranged in a straight line and a bent state, at least the connecting rod mechanism gradually eliminates the bent state and becomes a reversal of the change, and during the period when the bending starts again, the retainer is constructed to keep the state of capturing the bending needle line.

[0017] Furthermore, it can be configured that the retainer movement mechanism has a connecting rod mechanism, which is composed of two connecting rod units, and the connecting rod mechanism is configured such that: through input reciprocating movement, the straight line connecting the input side connection point and the output side connection point of each of the two connecting rod units repeats a proximal bending state bent in one direction, a straight line state arranged in a straight line, and a distal bending state bent in another direction, and compared with the distal bending state, the bending point between the two connecting rod units in the proximal bending state is set to be closer to the straight line state, and at least during the period from the straight line state to the proximal bending state and the time when the connecting rod mechanism becomes the straight line state again, the retainer is configured to continue the state of capturing the bending needle line.

[0018] Furthermore, the retainer movement mechanism can be constructed such that the retainer movement mechanism comprises: an input side rotating member which is arranged on the input side and rotates within a certain range, an output side rotating member which is arranged on the output side and rotates within a certain range, and a displacement transmission mechanism which transmits displacement from the input side rotating member to the output side rotating member, wherein the displacement transmission mechanism temporarily reduces the displacement transmission amount from the input side rotating member to the output side rotating member according to the relationship between the tangential direction component in the rotational displacement of the input side rotating member and the tangential direction component in the rotational displacement of the output side rotating member.

[0019] Furthermore, it can be configured such that the input-side rotating component has a first input arm portion and a first output arm portion extending from a first rotation center in different radial directions, and the driving force input from the first input arm portion is output from the first output arm portion as a rotational force around the first rotation center; and the output-side rotating component has a second input arm portion and a second output arm portion extending from a second rotation center in different radial directions, and the driving force input from the second input arm portion is output from the second output arm portion as a rotational force around the second rotation center.

[0020] The displacement transmission mechanism comprises: a groove portion, which is arranged on the first output arm portion or the second input arm portion and extends parallel to the radial direction passing through the first rotation center or the second rotation center; and a sliding part, which is arranged on the second input arm portion or the first output arm portion and moves along the groove portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a perspective view showing a sewing machine in which the mechanism according to one embodiment of the present invention is built-in.

[0022] Figure 2 This is a perspective view showing an extracted range including the retainer moving mechanism (link mechanism) of the first embodiment, and shows a state in which the retainer is most advanced (entered).

[0023] Figure 3 This is a perspective view showing an extracted range including the link mechanism of the first embodiment, and shows a state in which the retainer is fully retracted (retracted).

[0024] Figure 4A 1 is a perspective view of the main part showing the positional relationship between the retainer and the looper of the link mechanism of the first embodiment, and Figure 3 corresponding to the status.

[0025] Figure 4B 1 is a perspective view of the main part showing the positional relationship between the retainer and the looper of the link mechanism of the first embodiment, and Figure 2 corresponding to the status.

[0026] Figure 5 It is a perspective view showing the positional relationship among the needle, the looper, and the looper thread (the holder is not shown) in the first embodiment in the order of operation.

[0027] Figure 6 It is a perspective view showing the positional relationship among the needle, the looper, the needle thread, and the looper thread (the holder is not shown) in the first embodiment in the order of operation.

[0028] Figure 7 It is a stereoscopic diagram showing the positional relationship among the needle, the looper, the retainer, the needle thread, and the looper thread in the first embodiment in the order of operation.

[0029] Figure 8 It is a stereoscopic diagram showing the positional relationship among the needle, the looper, the retainer, the needle thread, and the looper thread in the first embodiment in the order of operation.

[0030] Fig. 9 It is a perspective view showing the positional relationship among the needle, the looper, the holder, and the looper thread (the needle thread is not shown) in the first embodiment in the order of operation.

[0031] Fig.10 It is a perspective view showing the positional relationship among the needle, the looper, the holder, and the looper thread (the needle thread is not shown) in the first embodiment in the order of operation.

[0032] Fig.11 : is a graph showing the change of the entry state of the retainer in the first embodiment.

[0033] Fig.12 This is another graph showing changes in the advancing state of the retainer in the first embodiment.

[0034] Fig.13 This is a perspective view showing an extracted range including the retainer moving mechanism (link mechanism) of the second embodiment, and shows a case where the retainer is in a normal speed state (when the needle is at the top dead center position).

[0035] Fig.14 It is a perspective view showing an extracted range including the link mechanism of the second embodiment, and shows a case where the retainer is in a low speed state (when the needle is at the bottom dead center position).

[0036] Fig.15 : is a graph showing the change of the entry state of the retainer in the second embodiment.

[0037] Fig.16 It is a perspective view showing an extracted range including the cage moving mechanism according to the third embodiment.

[0038] Fig.17 The retainer movement mechanism of the third embodiment is Fig.16 A stereoscopic view when viewed from the opposite side.

[0039] Fig.18 It is an exploded perspective view showing a cage moving mechanism according to a third embodiment.

[0040] Fig.19 It is an explanatory diagram showing the operation of the cage moving mechanism according to the third embodiment. DETAILED DESCRIPTION

[0041] Next, the embodiments of the present invention are listed for explanation. The sewing machine 1 of the present embodiment is a sewing machine 1 that can form a looped stitch, wherein the loop is a looped shape in which the bent needle thread Lb is expanded. The sewing machine 1 is mainly used to form a double chain loop stitch, but can also cope with other stitches such as flat stitches formed using a bent needle thread. In addition, the "double chain loop stitch" includes both single-needle double chain loop stitch and multi-needle double chain loop stitch. In addition, the up and down directions in the following description are directions in the embodiment.

[0042] First embodiment

[0043] like Figure 1 As shown in FIG. 1 , a sewing machine 1 having a mechanism of the present embodiment (first embodiment) built therein has a cylinder 2 that supports the cloth during sewing. In addition, a sewing machine 1 having a mechanism of the second embodiment described later built therein has the same appearance. The cloth is fed along the long side direction of the cylinder 2. In the present embodiment, the cloth is fed from the cylinder 2. Figure 1 The cloth is fed from the right to the left and sewn. A sewing part ( Figure 1 The mark "3" in the figure does not represent the needle 3 itself, but is used to mark its approximate position. The operator (operator) performing the sewing operation is located relative to the sewing machine 1. Figure 1 Here, the sewing machine 1 of the present embodiment is a sewing machine specifically used for sewing fabric into a cylindrical shape. Therefore, compared with a sewing machine that feeds fabric orthogonally to the long side direction of the cylinder, for example, the cylinder 2 needs to be formed thinner. Since the internal space of the cylinder 2 is also small, it should be noted that there are space limitations when configuring the internal components. In addition, the mark "OP" is added to the necessary figures for explanation, but the positional relationship in the figures without the mark is the same as that in the figures with the mark.

[0044] In the sewing machine 1 of this embodiment (the same applies to the second embodiment described later), the main parts related to the formation of the stitches are Figure 4A , Figure 4B The needle 3, looper 4, and retainer 5 are shown. The structures of the needle 3 and the looper 4 are the same as those known in the art. The needle 3 is connected to the needle thread La (see Figure 6 The needle plate 21 is held by the retainer 3 and moves up and down through the needle plate 21. In this embodiment, a plurality of (specifically four) needles 3 are provided. In the prior art, the retainer needle and the sewing needle are arranged in parallel, but in this embodiment, there is no retainer needle, and only the sewing needle 3 is provided as the needle that penetrates the fabric.

[0045] The bent needle 4 is, for example, Figures 5 to 10 The shape shown, the bending needle 4 pairs of bending needle line Lb (refer to Figure 5 etc.) and reciprocates in the space below the needle plate 21 in the cylinder body 2, such as Figures 6 to 8 As shown, the looper thread Lb is wound around the needle thread La. As shown in the figure, the looper 4 has a curved shape that is slightly convex upward. Figure 5As shown, the looper thread Lb can move through the inside of the looper 4 from the base end portion to the front end portion thereof. The looper 4 of the present embodiment reciprocates in a direction orthogonal to the direction in which the cloth is fed to the cylinder 2 (the width direction of the cylinder 2). Therefore, in the present embodiment, the looper thread Lb can be swung left and right relative to the cloth feeding direction by the looper 4, so that the stitch itself can be formed even without using the retainer 5. Therefore, the retainer 5 described below is not a necessary structure for forming the stitch. The retainer 5 of the present embodiment retains the looper thread Lb pulled out by the looper 4 when forming a double chain loop stitch, etc., and is a structure for achieving a desired extended stitch of the looper thread Lb as a result.

[0046] The retainer 5 reciprocates in the space below the needle plate 21 in the cylinder 2 and captures the looper thread Lb held by the looper 4. The retainer 5 in the mechanism of this embodiment is connected to Figure 2 and Figure 3 The link mechanism 6 shown as the retainer movement mechanism converts the driving force of the main shaft (not shown) and transmits it to the retainer 5 to make it reciprocate. Unlike the conventional retainer needle, the retainer 5 does not penetrate the fabric by the reciprocating movement. Figure 7 As shown, the retainer 5 is formed by bending a plate-like body. The flat base 51 is mounted on the retainer support body 8 that swings through the link mechanism 6. In this embodiment, the fixing hole 511 is mounted in a manner that is consistent with the mounting portion 82 of the retainer support body 8. In addition, the rotation center of the retainer 5 is consistent with the rotation support portion 81 of the retainer support body 8 (the rotation center of the swing). A connecting portion 52 bent in the plate thickness direction is formed at the upper end of the base 51, and a front end portion 53 that is orthogonal to the extension direction of the connecting portion 52 and protrudes is formed at the front end of the connecting portion 52. The base 51, the connecting portion 52, and the front end portion 53 are integrated. The looper thread Lb is hooked by the front end portion 53 (more specifically, the portion of the front end portion 53 close to the connecting portion 52), so that the retainer 5 captures the looper thread Lb. The front end portion 53 of the retainer 5 reciprocates in a direction perpendicular to the reciprocating direction of the looper 4 (a direction along the long side direction of the cylinder 2). Therefore, the moving direction of the front end portion 53 of the retainer 5 that hooks the looper wire Lb is perpendicular to the moving direction of the looper 4 (see Figure 7 direction of movement as indicated by the arrow in the figure).

[0047] The link mechanism 6 transmits the driving force from the driving source (motor not shown) of the sewing machine 1 to the retainer 5, and at the same time changes the motion state of the retainer 5. The link mechanism 6 of this embodiment connects the transmission rod 7 that reciprocates in the axial direction (up and down) by the driving force of the main shaft and the retainer support body 8 that supports the retainer 5. In addition, the main shaft is a rotating component, and is converted into reciprocating movement by a conversion mechanism such as an eccentric mechanism between the main shaft and the transmission rod 7. The link mechanism 6 is composed of a first component 61 to a sixth component 66, and the first component 61 to the sixth component 66 are connected in a manner that can rotate with each other from the base end side of the cylinder 2 to the front end side.

[0048] The first component 61 and the third component 63 are respectively in a V-shape of different shapes, and the front end portions of the V-shape rotate around the rotation fulcrum of the folded portion of the V-shape. The first component 61 is connected to the end of the transmission rod 7. The second component 62, the fourth component 64 to the sixth component 66 are respectively in an I-shape (straight rod shape), and the two end portions in the long side direction are connected to other components in a rotatable manner. The fifth component 65 is a component that extends between the base end and the front end of the cylinder body 2 and is longer than the other components.

[0049] In this embodiment, what is important is the relationship between the transmission rod 7 that moves up and down and the first to third components 61 to 63 in the case where the retainer 5 captures the looper line Lb. The first component 61 (the part on the opposite side of the transmission rod 7 in the V-shape, i.e., the output arm 611) and the second component 62 that are link units, and the relationship between the straight lines connecting the input side connection point and the output side connection point in the two components 61 (611) and 62 are as follows: Figure 2 The straight state in which the retainer 5 is arranged in a straight line on the same straight line as in the connection direction X shown corresponds to the state in which the retainer 5 is in the most advanced (entered) state. There is no particular limitation on the bending state and changes of the output arm portion 611 of the first component 61 and the second component 62, and various settings can be made, but according to the bending state initially described in this embodiment, the straight state will appear twice in one cycle of the reciprocating movement of the transfer rod 7 as the input side. In the first straight state, the transfer rod 7 is in a continuous descent at that moment. When the transfer rod 7 further descends and reaches the lowermost end, the output arm portion 611 of the first component 61 and the second component 62 are moved from Figure 2The state shown becomes a "<" shape (or a "V" shape tilted to the right) of the proximal bending state. In addition, the bend of the "<" in the proximal bending state is very small (the angle is a few degrees), and it is difficult to distinguish it from the straight state in appearance, so it is not shown in the figure. When the transmission rod 7 turns to rise, the angle of the "<" becomes larger, and after the second straight state, the output arm portion 611 of the first component 61 and the second component 62 change to a ">" shape (or a "V" shape tilted to the left), becoming Figure 3 The distal bending state shown is the bending state in the connection direction Y. Here, the transfer rod 7 reaches the uppermost end. When the transfer rod 7 turns to descend, the angle of the “>” character becomes larger and returns to Figure 2 The straight state shown. This action is repeated with the up and down reciprocating movement of the transmission rod 7. In this case, the states of the change related to bending are the proximal bending state and the distal bending state. In addition, compared with the distal bending state, the bending point between the first component 61 (output arm 611) and the second component 62 in the proximal bending state is set closer to the straight state.

[0050] By means of the link mechanism 6 configured in such a manner, the reciprocating movement of the retainer 5 is made such that the retainer 5 moves at a lower speed than before and after the retainer 5 at a certain range of positions in the space below the needle plate 21 for a certain period of time, thereby becoming a micro-motion state, and the state of capturing the looper thread Lb can be continued. The certain period of time associated with the low-speed movement is included in the period of capturing the looper thread Lb from the retainer 5 ( Figure 7 from the instant shown) to the moment when the bending needle 4 starts the reversal of the movement direction associated with the reciprocating movement (immediately after Fig.10 In addition, the certain range related to the low-speed movement is the range between the return position where the retainer 5 is in the most advanced (entered) state of the front end 53 and the position near the return position, away from the return position in the backward direction. The detailed description of "near" will be described later, but it refers to a range of less than 3% of the total stroke amount (corresponding to the distance from the most advanced position to the most retreated position) related to the reciprocating movement of the retainer 5.

[0051] Before and after the first component 61 (output arm 611) and the second component 62 of the link mechanism 6 become in a straight line state, a relationship is formed that is roughly common to the tangents of the rotational trajectories of the components 61 (611) and 62 (tangents that are perpendicular to the axial direction of the components 61 (611) and 62). While this relationship is established, approximately 100% of the driving force transmitted from the first component 61 as the driving side to the second component 62 as the driven side is the force of the directional component along the tangent direction. In other words, the force of the directional component perpendicular to the tangent direction is approximately 0%. On the other hand, the branch portion of the V-shaped third component 63 on the side that receives the driving force from the second component 62 is set to be perpendicular to the axial direction of the second component 62 (refer to Figure 2 ). Therefore, in the above-mentioned directional component, the third component 63 hardly rotates due to the driving force of the second component 62. Therefore, the retainer 5 connected to the link mechanism 6 (located on the downstream side of the third component 63 in the force transmission direction) is moved at a low speed (is in a state of being almost motionless). As described above, in this embodiment, the directional component of the force accompanying the rotation of the components constituting the link mechanism 6 is used to reduce the transmission amount of the driving force to other components, so that the retainer 5 can be moved at a low speed.

[0052] In addition, focusing on the proximal bent state, during the period when the link mechanism 6 passes through the proximal bent state from the straight state to the straight state again, the retainer 5 can be reciprocated at a smaller distance than during the period when the link mechanism 6 passes through the distal bent state to the straight state again, so the retainer 5 can be moved at a lower speed than before and after.

[0053] When the retainer 5 to which the driving force is transmitted through the connecting rod mechanism 6 reciprocates, it becomes the above-mentioned micro-motion state in the time interval of the reversing action on one side of the needle line Lb. Here, the above-mentioned micro-motion state means that the reversal of the retainer 5 is not performed immediately as in the past (patent document 1 (Japanese Patent Publication No. 2001-314681)), but is a state of movement in which the retainer 5 moves at a low speed for a certain period of time while reciprocating within a certain range (the retainer 5 performs "stepping" within a limited range). The above-mentioned "certain range" refers to a range in the direction of the reciprocating movement that is smaller than the entire range. Regarding the above-mentioned "small range", in the present embodiment, it is defined as: when the rotation angle of the main shaft of the sewing machine 1 is greater than 47°, the reciprocating movement amount of the retainer 5 corresponding to the rotation angle is less than 3% of the total stroke amount of the movement (corresponding to the distance from the most advanced position to the most retreated position).

[0054] Therefore, the change in the moving position of the retainer 5 in this embodiment is not a constant curved sine curve, but the speed of the retainer 5 is extremely reduced on one side of the two returns to the above-mentioned micro-motion state. Fig.11 In the process, there are two "peaks" corresponding to the return and a small "valley" between them, which changes to the state of "stepping". Fig.11 The horizontal axis "0°" corresponds to the most ascending position of the needle 3 (the top dead point of the needle bar (not shown) supporting the needle 3). And "180°" corresponds to the most descending position of the needle 3 (the bottom dead point of the needle bar). In addition, by changing the structure of the link mechanism 6, the movement position of the retainer 5 can be changed as shown in FIG. Fig.12 In this case, even in the same "stepping" state, as shown in the figure, there is a "peak" corresponding to the return, for example, the moving position of the retainer 5 changes in a manner such that the curvature of the sine curve is locally relaxed or a "flat" portion appears in the sine curve.

[0055] The link mechanism 6 is provided with a bending movable portion (in this embodiment, a combination of a first component 61 and a second component 62 as a link unit) that receives the reciprocating movement of the transmission rod 7 and moves in the most bent state on one side (the proximal bending state (not shown) / from Figure 2 The state is bent into Figure 3 The opposite "<" shape) and the most curved state on the other side (the distal curved state / Figure 3 In the present embodiment, it is set that the moment (moment) when the up-and-down reciprocating movement of the transmission rod 7 is switched from downward to upward is not consistent with the moment when the output arm portion 611 of the first component 61 and the extension direction of the second component 62 of the curved movable portion provided on the link mechanism 6 become straight (straight state). Moreover, in the present embodiment, it is set that when the curved movable portion becomes straight ( Figure 2 In the state of the curved movable portion (the "<" shape and the ">" shape), the front end portion 53 of the retainer 5 protrudes the most, and in the curved movable portion, the front end portion 53 retreats. Figure 3 Indicates the most retracted state. Therefore, after the output arm portion 611 of the first component 61 and the extension direction of the second component 62 become a straight line, they are also pressed by the transmission rod 7, and the bending of the output arm portion 611 of the first component 61 and the second component 62 will continue. Before and after becoming the bent state (specifically, the "<" shape), the output arm portion 611 of the first component 61 and the second component 62 become straight lines twice. The time between these two straight lines is the time when the retainer 5 becomes the said micro-motion state. Through such a relationship between the first component 61 (output arm portion 611) and the second component 62, the connecting rod mechanism 6 is in Fig.11In a manner that two peaks appear on the curve graph (horizontal axis 0° to 90°), the retainer 5 (especially the front end portion 53 that captures the bending needle line Lb) is retreated from the return position within the certain range, then advanced to the return position, and then retreated again.

[0056] Here, the case of setting the bending state and the change of the output arm portion 611 of the first component 61 and the second component 62 to other settings is described. The bending state is set as follows: the output arm portion 611 of the first component 61 and the second component 62 change to three states: a straight state, a proximal bending state (a "<" shape), and a distal bending state (a ">" shape). In contrast, as other settings, for example, it can also be set to change to two states, a straight state and a bending state. In this case, the states that become reversals in the changes related to the bending are the straight state and the bending state. The "bending state" is the distal bending state ( Figure 3 Even with this structure, the retainer 5 can be moved at a low speed.

[0057] As a further other setting, it can also be set to change to two states: a state that is not the straight state, but a state that is bent in the same direction as the bent state and is gentler than the bent state (called a "quasi-straight state") and a bent state. In this case, the states that are turned back in the change related to the bending are the quasi-straight state and the bent state. Even with this structure, the low-speed movement of the retainer 5 can be achieved. Therefore, the link mechanism 6 can be set in various ways to repeatedly change in a part or all of the range between the straight state and the bent state.

[0058] Then, in Figures 5 to 10 In the figure, needles 3 (four), curved needles 4, retainers 5, needle threads La, and curved needle threads Lb are taken out, and the positional relationship of each part is indicated and explained in the order of action. In addition, in some figures, the illustration of retainer 5 and needle thread La is omitted for the purpose of avoiding the complication of the relationship and the content of the illustration. In addition, the arrows attached to each part indicate the direction of movement. In addition, the arrow with a horizontal bar indicates the arrival at the return position. Each figure is based on the line of sight from the front end side of the cylinder 2 to the base end side, that is, from the opposite side of the operator to the operator ( Figure 5 The direction is also expressed based on the viewpoint.

[0059] Figure 5 The state in which the looper 4 moves to the right in the figure is shown. At this time, the needle 3 is descending (the needle thread La is omitted in the figure). Figure 6This shows the state after the moving direction of the looper 4 is reversed from the right to the left in the figure. At this time, the needle 3 is rising after reaching the lower dead point (lowest position). Then, the needle thread La is picked up by the looper 4 that enters under the needle 3. At this time, the looper thread Lb passes from right to left in the loop of the needle thread La. Figure 7 The state where the looper 4 moves to the left in the figure is shown. The retainer 5 moves so as to approach the looper 4, hooks and captures the looper thread Lb passing through the loop of the needle thread La, and starts to retain the looper thread Lb. Figure 8 The figure shows that the looper 4 moves further to the left and is located at the leftmost position in the figure. At this time, the needle 3 is at the top dead center (uppermost position). The retainer 5 is maintained at a certain range of positions and continues to capture the looper line Lb. Fig. 9 The figure shows the state after the moving direction of the looper 4 is reversed from the left to the right. At this time, the needle 3 descends (the needle line La is omitted in the figure) and intersects the looper 4. The retainer 5 is also kept in a certain range at this moment and continues to capture the looper line Lb. Fig.10 The state in which the looper 4 moves further to the right in the figure and becomes the rightmost position in the figure. At this time, the needle 3 is at the bottom dead center (the needle line La is omitted in the figure). The retainer 5 will then retreat and leave the looper line Lb. By the way, the position where the retainer 5 captures the looper line Lb is set to the same position as the retainer needle provided with the needle in the past to capture the looper line in the state of penetrating the cloth.

[0060] Regarding the movement of the retainer 5, at least when the looper 4 is located at the far left in the figure ( Figure 8 ) to the intersection of needle 3 and curved needle 4 ( Fig. 9 ), the retainer 5 is in a state of moving at an extremely low speed. As a result, since the position of the portion of the looper thread Lb held by the retainer 5 is almost unchanged relative to the needle thread La, the looper thread Lb is pulled out as the looper 4 moves to the left, and the pulled-out portion can form a loop of the looper thread Lb that is more expanded (i.e., "looser") than before. Therefore, corresponding to the capture of the looper thread Lb by the retainer 5, a desired expanded loop-shaped stitch of the looper thread Lb can be formed.

[0061] At this time, since the retainer 5 is in a state of moving at an extremely low speed, the amount of movement of the retainer 5 during the period of holding the looper thread Lb can be reduced compared to the structure in the past (Patent Document 1 (Japanese Patent Laid-Open No. 2001-314681)) in which the retainer continuously reciprocates at a constant speed to hold the looper thread. Therefore, the amount of movement of the retainer 5 can be reduced, and the volume occupied by the retainer 5 inside the cylinder 2 can be reduced accordingly, so that the retainer 5 can be compactly stored in the cylinder 2.

[0062] Here, in Fig.11The moving trajectory of the retainer 5 is schematically shown in the graph. The horizontal axis of the graph is the time axis (more specifically, it is an angle representation based on the top dead point and the bottom dead point of the needle 3 and the needle bar supporting it), and the vertical axis represents the displacement related to the reciprocating movement. As a previous example, the retainer 5 described in the patent document 1 performs a simple reciprocating movement. Although not shown in the figure, the moving trajectory of the retainer 5 is a simple sine curve. If the curved needle line Lb is to be maintained for a long time in such a simple reciprocating state, it is necessary to increase the reciprocating stroke of the retainer 5. If so, there is a possibility that the reciprocating range of the retainer 5 cannot be accommodated inside the cylinder 2.

[0063] On the other hand, the movement trajectory of the retainer 5 in this embodiment is, for example, Fig.11 As shown. As shown on the graph, two small low peaks are formed in the range including the horizontal axis 0° to 90°. Two small peaks are formed on the graph, that is, the front end 53 of the retainer 5 reciprocates within a small range. In this way, by making the retainer 5 "step" within the limited range relative to the bending needle 4, the retainer 5 does not turn back immediately, but the retainer 5 can stay in the narrow range of the reciprocating movement range for a certain period of time. In this way, the bending needle line Lb can be maintained without increasing the reciprocating movement range of the retainer 5.

[0064] As mentioned above, although the 1st embodiment of this invention is described, this invention is not limited to this embodiment, Various changes can be made within the range which does not deviate from the summary of this invention.

[0065] For example, the structure for moving the retainer 5 at a low speed for a certain time at a position within a certain range, i.e., a low-speed moving mechanism, is not limited to the link mechanism of the above-mentioned embodiments, but can be implemented by various structures. For example, as a mechanical structure, a structure having a cam, a gear without teeth formed locally, a combination of multiple gears approaching and separating, a clutch mechanism, and a brake mechanism that decelerates by friction can be considered. In addition, as an electrical structure, a structure having a circuit that connects and disconnects the transmission of the driving force in a specified time period can be considered. In addition, in the above-mentioned embodiments, a low-speed moving mechanism is provided at one part of the driving force transmission path, but it is also possible not to use this structure, but to separately provide the low-speed moving mechanism at multiple parts, and the separated mechanisms are configured to act simultaneously or with a time lag.

[0066] Second embodiment

[0067] In addition, the driving force for moving the retainer 5 can also be obtained from the axis for driving the looper 4, that is, the looper axis or the conveying table. In addition, the retainer 5 can also be moved by a driving mechanism independent of the mechanism for driving other parts of the sewing machine. Hereinafter, the "second embodiment" will be illustrated.

[0068] As a second embodiment, Fig.13 and Fig.14 An example of a structure in which the driving force of the retainer 5 is obtained from the looper shaft 11 is shown. Fig.15 The moving trajectory of the retainer 5 in the second embodiment is schematically shown in the curve diagram. In the second embodiment, the axial direction of the retainer shaft 12 is set to be parallel to the bending needle shaft 11, wherein the bending needle shaft 11 is driven by a main shaft (not shown) connected to the base end side. A retainer support portion 14 is integrally provided at the front end of the retainer shaft 12. The axial directions of the bending needle shaft 11 and the retainer shaft 12 are along the length direction of the cylinder 2, and the distance between the centers of each axis is constant. The bending needle shaft 11 and the retainer shaft 12 are connected by a connecting rod mechanism 13 in a manner capable of transmitting driving force. The connecting rod mechanism 13 includes a bending needle side connecting rod body 131 and a connecting connecting rod body 132 as a connecting rod unit. The connecting connecting rod body 132 is connected to a connecting rod receiving portion 121 integrally provided on the base end side of the retainer shaft 12. The bending needle shaft 11 rotates within a specified angle range in order to move the bending needle 4 forward and backward. Correspondingly, the connecting rod mechanism 13 repeats Fig.13 The status shown is the same as Fig.14 The status shown (in detail, more than Fig.14 In the state shown, the bending needle side connecting rod body 131 and the connecting connecting rod body 132 are slightly Fig.13 The state shown is the opposite bending state).

[0069] The retainer 5 in the second embodiment has a rod-like body that is bent into an "L" shape to form a hook needle shape. The base 54 extending in the radial direction of the retainer 5 is mounted on the retainer support portion 14, and the front end portion 55 integrally provided on the radial outer side of the base 54 is used to catch the looper line Lb by hooking it. As described above, the looper shaft 11 is parallel to the retainer shaft 12, and the looper 4 and the retainer 5 rotate (swing) at the front end of each shaft, so that the front end portion 55 of the retainer 5 reciprocates in the direction along the looper 4 (i.e., the direction orthogonal to the length direction of the cylinder 2).

[0070] By adjusting the timing of the bending state and the straight state in the link mechanism 13, the retainer 5 of the second embodiment can be in the above-mentioned micro-motion state in the time interval of the return action of the retaining needle thread (not shown) when reciprocating. Fig.15As shown in the figure, the interval where the needle 3 is at the lowest position (the lower dead point of the needle bar) across the "180°" corresponding to the horizontal axis corresponds to the time interval, where two small low peaks are formed. This state is equivalent to Fig.14 The state shown in FIG. 1 and the state of the opposite bending are between the state shown in FIG. 1 and the state of the opposite bending. The timing of the capture of the looper thread Lb by the front end portion 55 of the retainer 5 is based on the capture by the retainer needle in the past. In addition, the reason why the position of the peak is different from that of the first embodiment is that the relationship between the reciprocating directions of the looper 4 and the retainer 5 is orthogonal in the first embodiment, but parallel in the second embodiment, so the timing of retaining the looper thread is different in each embodiment. The above is the description of the second embodiment.

[0071] Third embodiment

[0072] Here, in the first embodiment, as Figure 2 and Figure 3 As shown, the connection of adjacent components 61~66 is a connection that can rotate around an axis at a certain position (a combination of a round hole and a round rod-shaped axis). However, it is not limited to this, and it can also be configured as follows: in one or more connection parts, the rotation axis (round rod-shaped) is located inside the formed long hole or groove portion, and the rotation axis rotates and is offset within the extension range of the long hole or groove portion. By configuring in this way, even if one of the adjacent components 61~66 (the upstream side of the driving force transmission path) moves, its displacement will not be transmitted to the other (the downstream side of the driving force transmission path), or it will only be transmitted slightly, so that the retainer 5 located at the most downstream side of the driving force transmission path can be in a state of moving at an extremely low speed in the same manner as the above-mentioned embodiment. As a specific example, the form of setting the groove portion is described as the "third embodiment" below. In addition, for the structure that is common to the first embodiment, the same mark is marked in the third embodiment for description (for the convenience of description, there are also structures with different names from the first embodiment).

[0073] The retainer moving mechanism 6 in the third embodiment includes, in the order of transmission of the driving force for moving the retainer 5, an input-side rotating member 61 provided on the input side and rotating within a certain range, an output-side rotating member 63 provided on the output side and rotating within a certain range, and a displacement transmission mechanism 67 for transmitting displacement from the input-side rotating member 61 to the output-side rotating member 63. The displacement transmission mechanism 67 temporarily reduces the amount of displacement transmission from the input-side rotating member 61 to the output-side rotating member 63 according to the relationship between the tangential direction component of the rotational displacement of the input-side rotating member 61 and the tangential direction component of the rotational displacement of the output-side rotating member 63.

[0074] The angle relationship of the tangential direction component is described below. When the tangential direction component of the rotational displacement of the input-side rotating member 61 and the tangential direction component of the rotational displacement of the output-side rotating member 63 are in an orthogonal relationship, even if the input-side rotating member 61 rotates, since the component of the rotational force of the input-side rotating member 61 that is equivalent to the tangential direction component of the rotational displacement of the output-side rotating member 63 is 0, it will not be transmitted to the output-side rotating member 63 as a rotational force. In other words, the displacement transmission amount from the input-side rotating member 61 to the output-side rotating member 63 is temporarily reduced (0 in this case). In addition, the rotational force of the input-side rotating member 61 is only absorbed by the positional deviation in the displacement transmission mechanism 67.

[0075] In the third embodiment, in a manner corresponding to the orthogonal relationship between the tangential direction components of the rotational displacements of the input-side rotational member 61 and the output-side rotational member 63, at the end of the rotational range of the input-side rotational member 61 (the position where the first output arm portion 613 becomes the upper end (top dead center) of the rotational range), the tangential direction component of the rotational displacement of the input-side rotational member 61 is set to be as large as the extension direction of the groove portion 671 (see Fig.19 The rotation trajectory of the first output arm 613 is shown in FIG.

[0076] Incidentally, the temporary reduction of the displacement transmission amount from the input-side rotating member 61 to the output-side rotating member 63 according to the angular relationship of the tangential direction component is also applicable to the connection between the first member 61 as the input-side rotating member and the third member 63 as the output-side rotating member in the link mechanism 6 as the retainer movement mechanism of the first embodiment, and the second member 62 of the first embodiment is equivalent to the displacement transmission mechanism 67 described in the third embodiment. In the first embodiment, the first member 61 (the output arm portion 611) and the second member 62 are bent, thereby generating a positional offset, thereby absorbing the rotational force of the input-side rotating member 61. Similarly, the temporary reduction of the displacement transmission amount from the input-side rotating member 61 to the output-side rotating member 63 is also applicable to the connection between the looper-side link body 131 and the link receiving portion 121 in the link mechanism 13 as the retainer movement mechanism of the second embodiment, and the connection link body 132 of the second embodiment is equivalent to the displacement transmission mechanism 67 described in the third embodiment. Here, in the second embodiment, the looper side connecting rod body 131 is equivalent to the input side rotating member 61 of the third embodiment, and the retainer shaft 12 is equivalent to the output side rotating member 62 of the third embodiment. In the second embodiment, the looper side connecting rod body 131 and the connecting connecting rod body 132 are bent, thereby generating a positional offset, thereby absorbing the rotational force of the looper side connecting rod body 131. Therefore, even in the first embodiment and the second embodiment, which have different specific structures, at least a part of the function played by the third embodiment is the same.

[0077] Specifically, the third embodiment is as follows Figures 16 to 19 In addition, in particular, the fourth member 64 and the fifth member 65, although their shapes are similar to those of the first embodiment (see Figure 2 ) are quite different, but there is no significant difference in function. The input side rotating member 61 has a first input arm portion 612 and a first output arm portion 613 (in different radial directions) extending from the first rotation center 61c. Fig.19 The output-side rotating member 63 includes a second input arm 631 and a second output arm 632 (in the figure, the rotational movement is indicated by a curved arrow) that outputs the driving force input from the first input arm 612 by the movement of the transmission rod 7 as a rotational force around the first rotation center 61c from the first output arm 613. Fig.19 (The rotational action is indicated by the curved arrow in the figure), the driving force input from the second input arm portion 631 is output from the second output arm portion 632 as a rotational force around the second rotation center 63c.

[0078] The displacement transmission mechanism 67 includes: a groove portion 671 provided on the second input arm portion 631 and extending parallel to the radial direction passing through the second rotation center 63c; and a sliding member 672 provided on the first output arm portion 613 and moving along the groove portion 671. The cross-sectional shape of the groove portion 671 is formed into a rectangular shape, and is formed into a constant shape in the extension direction. The sliding member 672 is composed of a shaft portion 6721 integrally provided on the first output arm portion 613 and a slider portion 6722 rotatably provided around the shaft portion 6721. The shaft portion 6721 is in the shape of a round bar, and the slider portion 6722 is in the shape of a rectangular parallelepiped, and a hole (the illustrated form is a through hole, but it may also be a bottomed hole) is provided in the center for the shaft portion 6721 to enter. The slider portion 6722 abuts against the inner surface of the groove portion 671 and moves along the extension direction of the groove portion 671. That is, the sliding member 672 slides relative to the groove portion 671.

[0079] like Fig.19 As shown, the displacement transmission mechanism 67 composed of a combination of a groove portion 671 and a sliding member 672 can rotate the input side rotating member 61 and the output side rotating member 63 while maintaining a constant linear distance between the first rotation center 61c of the input side rotating member 61 and the second rotation center 63c of the output side rotating member 63. In other words, the displacement transmission mechanism 67 is configured to allow positional deviation between the input side rotating member 61 and the output side rotating member 63 while transmitting displacement from the input side rotating member 61 to the output side rotating member 63. By changing with this positional deviation, the displacement transmission amount can be temporarily reduced. The change in the moving position of the retainer 5 can be related to the change in the displacement transmission amount. Fig.12 same.

[0080] In addition, the displacement transmission mechanism 67 is not limited to the above-described structure in the relationship between the input-side rotating member 61 and the output-side rotating member 63. The portion where the groove 671 and the sliding member 672 are provided may also be opposite to the above-described structure. That is, the displacement transmission mechanism 67 may be configured to have: a groove 671 provided on the first output arm 613 or the second input arm 631 and extending parallel to the radial direction passing through the first rotation center 61c or the second rotation center 63c; and a sliding member 672 provided on the second input arm 631 or the first output arm 613 and moving along the groove 671.

[0081] The structure and function of the embodiment are summarized as follows. The embodiment is a sewing machine 1, which is provided with: a needle 3, which holds the needle thread La and moves up and down through the needle plate 21; a curved needle 4, which holds the curved needle thread Lb and reciprocates in the space below the needle plate 21 so that the curved needle thread Lb is wound around the needle thread La; a retainer 5, which reciprocates in the space below the needle plate 21 and captures the curved needle thread Lb; a retainer movement mechanism 6, which transmits the driving force from the driving source to the retainer 5 and changes the movement state of the retainer 5, and the retainer movement mechanism 6 makes the retainer 5 reciprocate at a certain range of positions in the space below the needle plate 21 and moves at a lower speed than before and after for a certain period of time, thereby continuously keeping the retainer 5 in a state of capturing the curved needle thread Lb.

[0082] According to this structure, the retainer movement mechanism 6 allows the retainer 5 to reciprocate at a position within a certain range in the space below the needle plate 21 and at a lower speed than before and after for a certain period of time, thereby maintaining the state in which the retainer 5 captures the bent needle thread Lb. Therefore, compared with a structure in which the retainer 5 is not moved at a low speed, since the bent needle thread Lb can be held for a long time by a reduced speed during the slow movement, the range of the reciprocating movement of the retainer 5 can be kept constant. In addition, the "slow-speed movement" also includes a case where the speed is 0 (stop state). In addition, if the case where the speed is 0 is described in another way, it becomes "the retainer movement mechanism 6 allows the retainer 5 to reciprocate at a position within a certain range in the space below the needle plate 21 and at a lower speed than before and after for a certain period of time, or allows the retainer to reciprocate in a standby state at a speed of 0".

[0083] Furthermore, the certain range involved in the low-speed movement of the retainer 5 by the retainer movement mechanism 6 can be: the range between the turning position where the retainer 5 reverses from the forward direction to the backward direction, and a position near the turning position and away from the turning position toward the backward direction.

[0084] In addition, the holder moving mechanism 6 can also cause the holder 5 to retreat once from the return position within the certain range, then advance it again to the return position, and then retreat it again.

[0085] According to these structures, the retainer 5 repeatedly moves forward and backward at a low speed near the reversing position. Therefore, the structure of the retainer movement mechanism 6 can be simplified compared to the case where it is completely stopped within a certain period of time. In addition, the "complete stop within a certain period of time" does not include the case of stopping instantly with reversing.

[0086] Then, the retainer movement mechanism 6 has a connecting rod mechanism 6, which is composed of two connecting rod units 62. The connecting rod mechanism 6 can also be constructed as follows: through input reciprocating movement, the straight lines connecting the input side connection points and the output side connection points of the two connecting rod units respectively change repeatedly within a part or all of the range between a straight line state arranged in a straight line and a bent state; at least the connecting rod mechanism 6 can be constructed so that the bent state gradually disappears and becomes a reversal of the change, and during the period when bending is started again, the retainer 5 continues to capture the bending needle line Lb.

[0087] According to this structure, the holder 5 can reciprocate by a small distance before and after the link mechanism 6 is in a straight state or a changed and folded state, so the holder 5 can be moved at a lower speed than before and after. Therefore, the link mechanism 6 can achieve low-speed movement.

[0088] Moreover, the retainer movement mechanism 6 has a connecting rod mechanism 6 composed of two connecting rod units 61, and the connecting rod mechanism 6 is constructed as follows: through input reciprocating movement, the straight line connecting the input side connection point and the output side connection point of the two connecting rod units 61 repeats the proximal bending state bent in one direction, the straight line state arranged in a straight line, and the distal bending state bent in another direction. Compared with the distal bending state, the bending point between the two connecting rod units 61 in the proximal bending state is set to be closer to the straight line state; at least it can be constructed so that the retainer 5 continues to capture the bending needle line Lb before the connecting rod mechanism passes through the proximal bending state from the straight line state to the straight line state again.

[0089] According to this structure, the retainer 5 can be reciprocated by a small distance during the period when the link mechanism 6 goes from the straight state to the proximal end curved state and then becomes the straight state again, so the retainer 5 can be moved at a lower speed than before and after. Therefore, the link mechanism 6 can realize low-speed movement.

[0090] Moreover, the retainer movement mechanism 6 comprises: an input side rotating part 61 which is arranged on the input side and rotates within a certain range, an output side rotating part 63 which is arranged on the output side and rotates within a certain range, and a displacement transmission mechanism 67 which transmits the displacement from the input side rotating part 61 to the output side rotating part 63. The displacement transmission mechanism 67 temporarily reduces the displacement transmission amount from the input side rotating part 61 to the output side rotating part 63 according to the angular relationship between the tangential direction component in the rotational displacement of the input side rotating part 61 and the tangential direction component in the rotational displacement of the output side rotating part 63.

[0091] According to this configuration, the cage 5 can be moved at a low speed by the angular relationship between the tangential direction component of the rotational displacement of the input-side rotational member 61 and the tangential direction component of the rotational displacement of the output-side rotational member 63 .

[0092] Moreover, the input-side rotating component 61 has a first input arm portion 612 and a first output arm portion 613 extending from a first rotation center 61c to different radial directions, and the driving force input from the first input arm portion 612 is output from the first output arm portion 613 as a rotational force around the first rotation center 61c. The output-side rotating component 63 has a second input arm portion 631 and a second output arm portion 632 extending from a second rotation center 63c to different radial directions, and the driving force input from the second input arm portion 631 is output from the second output arm portion 632 as a rotational force around the second rotation center 63c.

[0093] The displacement transmission mechanism 67 may have: a groove portion 671, which is provided in the first output arm portion 612 or the second input arm portion 632, and extends parallel to the radial direction passing through the first rotation center 61c or the second rotation center 63c; and a sliding part 672, which is provided in the second input arm portion 632 or the first output arm portion 612, and moves along the groove portion 671.

[0094] According to this structure, the combination of the groove portion 671 and the sliding member 672 enables the cage 5 to move at a low speed.

[0095] According to the embodiment, compared with a structure in which the retainer 5 is not moved at a variable speed, since the looper thread Lb can be held for a long time during low-speed movement, it is not necessary to increase the reciprocating range of the retainer 5. Therefore, it is possible to extend the time for the retainer 5 to hold the looper thread Lb without setting the reciprocating stroke of the retainer 5 to be large, and as a result, it is possible to achieve the effect of achieving a desired extended stitch of the looper thread Lb.

[0096] Description of Reference Numerals

[0097] 1 Sewing machine

[0098] 2 cylinder block

[0099] 21 Needle Plate

[0100] 3-pin

[0101] 4 Looper

[0102] 5. Retainer

[0103] 6 Retainer movement mechanism (first embodiment, third embodiment), link mechanism (first embodiment)

[0104] 61 connecting rod unit (first embodiment), first member (first embodiment), input side rotating member (third embodiment)

[0105] 61c First rotation center

[0106] 612 first input arm

[0107] 613 first output arm

[0108] 62 Link unit, second component (first embodiment)

[0109] 63 third member (first embodiment), output side rotating member (third embodiment)

[0110] 63c Second rotation center

[0111] 631 Second input arm

[0112] 632 second output arm

[0113] 67 Displacement Transmission Mechanism (Third Embodiment)

[0114] 671 slot

[0115] 672 sliding parts

[0116] 13 Retainer movement mechanism (second embodiment), connecting rod mechanism (second embodiment)

[0117] 131 Link unit (second embodiment), looper side link unit (second embodiment)

[0118] 132 connecting rod unit (second embodiment), connecting rod body (second embodiment)

[0119] La Needlework

[0120] Lb hook thread

[0121] OP is toward the operator side.

Claims

1. A sewing machine comprising: The needle holds the needle thread and moves up and down through the needle plate; A looper, which holds the looper thread and reciprocates in the space below the needle plate so that the looper thread is wound around the needle thread; A retainer reciprocates in the space below the needle plate and captures the looper thread; and The retainer movement mechanism changes the movement state of the retainer while transmitting the driving force from the driving source to the retainer. The retainer movement mechanism causes the retainer to reciprocate at a position within a certain range in the space below the needle plate and at a certain time at a lower speed than the front and back of the retainer, thereby maintaining the state in which the retainer captures the looper thread.

2. The sewing machine according to claim 1, The certain range involved in the low-speed movement of the retainer by the retainer movement mechanism is: The range is between a turning position where the retainer reverses from the advancing direction to the retreating direction and a position near the turning position and away from the turning position in the retreating direction.

3. The sewing machine according to claim 2, The holder moving mechanism causes the holder to retreat once from the return position within the certain range, then advances the holder to the return position again, and then retreats the holder again.

4. The sewing machine according to claim 1, The retainer movement mechanism has a link mechanism, which is composed of two link units. The link mechanism is configured such that, by inputting a reciprocating movement, the straight line connecting the input-side connection point and the output-side connection point of each of the two link units repeatedly changes in a part or all of a range between a straight state arranged in a straight line and a curved state. At least the link mechanism is configured so that the holder continues to capture the looper thread while the bent state is gradually eliminated and the change is reversed and the bending is started again.

5. The sewing machine according to claim 1, The retainer movement mechanism has a link mechanism, which is composed of two link units. The connecting rod mechanism is configured such that, by inputting a reciprocating movement, the straight line connecting the input side connecting point and the output side connecting point of each of the two connecting rod units repeats a proximal bending state in which the straight line is bent in one direction, a straight line state arranged in a straight line, and a distal bending state in which the straight line is bent in another direction, and the bending point between the two connecting rod units in the proximal bending state is set closer to the straight line state than in the distal bending state. At least during a period from when the link mechanism passes through the proximal end bent state from the straight state to when it becomes the straight state again, the retainer is configured to continue the state of capturing the looper thread.

6. The sewing machine according to claim 1, The retainer movement mechanism comprises: an input side rotating member provided on the input side and rotating within a certain range, an output side rotating member provided on the output side and rotating within a certain range, and a displacement transmission mechanism for transmitting displacement from the input side rotating member to the output side rotating member. The displacement transmission mechanism temporarily reduces the displacement transmission amount from the input side rotation member to the output side rotation member according to the relationship between the angles formed by the tangential direction component of the rotational displacement of the input side rotation member and the tangential direction component of the rotational displacement of the output side rotation member.

7. The sewing machine according to claim 6, The input-side rotating member includes a first input arm portion and a first output arm portion extending in different radial directions from a first rotation center, and the driving force input from the first input arm portion is output from the first output arm portion as a rotational force around the first rotation center. The output-side rotating member has a second input arm portion and a second output arm portion extending in different radial directions from a second rotation center, and the driving force input from the second input arm portion is output from the second output arm portion as a rotational force around the second rotation center. The displacement transmission mechanism comprises: a groove portion, which is arranged on the first output arm portion or the second input arm portion and extends parallel to the radial direction passing through the first rotation center or the second rotation center; and a sliding part, which is arranged on the second input arm portion or the first output arm portion and moves along the groove portion.

Images