Sewing machine

Abstract

The invention provides a sewing machine which not only can perform smooth sewing operation without hindering the sewing operation by a thread puller, but also is high in safety, good in appearance and convenient to use. The sewing machine is provided with a presser foot (1) for pressing cloth on a needle plate (18); a presser foot leg (8) supporting the presser foot (1); a thread puller (3) which has a thread hole (14) through which the thread passes up and down and which can rotate freely; the wire puller driving mechanism (4) drives the wire puller (3) to rotate; a reciprocating motion conversion mechanism (5) that converts the rotation of the upper shaft (7) into a linear reciprocating motion; and a link mechanism (6) that transmits the reciprocating motion generated by the reciprocating motion conversion mechanism (5) to the wire grip drive mechanism (4). And the wire puller (3) and the wire puller driving mechanism are arranged on the presser foot. And the connecting rod mechanism (6) is arranged on the presser foot leg (8).

Description

Technical Field

[0001] The invention relates to a sewing machine for forming decorative stitches on the upper surface of cloth. Background Art

[0002] In the past, in order to be able to carry out the upper surface decorative seam of cloth, a pair of left and right thread pullers and their driving mechanism (referring to following patent document 1) that are arranged on sewing machine are known.In this structure, in order to make the left and right thread pullers act symmetrically, the driving force of the driving shaft is distributed to each thread puller.

[0003] That is, the first support arm supporting one wire puller is fixed to the drive shaft and is directly driven by the drive shaft, and the second support arm supporting the other wire puller is driven by the drive shaft via a link mechanism connected to the first support arm.

[0004] In addition, in the prior art, the following structure is proposed: a strip-shaped thread puller is assembled on the presser foot, which can avoid contact with the thread puller from the outside and can be attached to the multifunction machine (see the following patent document 2). In this structure, a connecting rod mechanism that uses the movement of the needle bar as a driving source and transmits the driving force to the thread puller is arranged at a position away from the presser foot bar supporting the presser foot.

[0005] Furthermore, in the prior art, in order to prevent the thread puller from interfering with sewing and to ensure safety, a sewing machine having a mechanism capable of detachably attaching and detaching a thread puller driving device has been proposed (see Patent Document 3 listed below).

[0006] [Prior art literature]

[0007] Patent Literature

[0008] Patent Document 1: Japanese Utility Model Publication No. 54-102368

[0009] Patent Document 2: Japanese Patent Application Publication No. 2001-120864

[0010] Patent Document 3: Japanese Patent Application Publication No. 2003-169982 Summary of the invention

[0011] Problems to be solved by the invention

[0012] However, according to the structure described in Patent Document 1, the power transmission paths are different in the left and right wire pullers, so there is a disadvantage that the left and right wire pullers cannot move symmetrically due to gaps and wear of movable parts.

[0013] Furthermore, according to the structure described in Patent Document 2, the power transmission structure including the belt-shaped thread puller is exposed behind the presser foot, so that it may come into contact with the operator's fingers during sewing operations, and the appearance is also poor.

[0014] In addition, according to the structure described in Patent Document 3, if the upper surface decorative seam is not performed, the removed wire puller may be lost. Moreover, the removal and installation operations of the wire puller are complicated and inconvenient to use.

[0015] In view of the above problems, an object of the present invention is to provide a sewing machine which can not only perform smooth sewing operations without the thread puller interfering with the sewing operations, but also has high safety, good appearance and is easy to use.

[0016] Means for solving problems

[0017] In order to achieve this object, the present invention provides a sewing machine for forming decorative stitches on the upper surface of a cloth, characterized in that it comprises: a presser foot, which presses the cloth on a needle plate adjacent to a sewing needle that moves up and down; a presser foot leg, which supports the presser foot; a thread puller, which has a thread hole for the thread to pass through up and down and can rotate freely; a thread puller driving mechanism, which drives the thread puller to rotate; a reciprocating motion conversion mechanism, which is located above the needle plate and converts the rotation of the upper shaft into a linear reciprocating motion in the front and rear directions; and a connecting rod mechanism, which transmits the reciprocating motion generated by the reciprocating motion conversion mechanism to the thread puller driving mechanism, the thread puller and the thread puller driving mechanism are both arranged on the presser foot, and the connecting rod mechanism is arranged on the presser foot leg.

[0018] According to the present invention, since the thread puller and the thread puller driving mechanism are arranged on the presser foot, and the connecting rod mechanism is arranged on the presser foot leg, it is possible to prevent the rotating thread puller from contacting the fingers of the operator during sewing, and the sewing operation can be performed smoothly and safely. Moreover, for example, the power transmission component from the reciprocating motion conversion mechanism via the connecting rod mechanism to the thread puller driving mechanism can be exposed to a minimum, so that a simple appearance can be formed.

[0019] In addition, the present invention is characterized in that the presser foot has a pivot, which is located at a position further rearward than the sewing needle and extends up and down, and the thread puller has: a main body, which is supported by the pivot; a cam groove, which is formed on the main body and bent along a rotating track; and an arm, which extends forward from the main body and is formed with the thread hole, and the thread puller driving mechanism has: a slider, which moves forward and backward toward the pivot by the reciprocating motion transmitted from the reciprocating motion conversion mechanism via the connecting rod mechanism; and a cam follower, which is arranged on the slider and slides along the cam groove of the thread puller as the slider moves, thereby rotating the thread puller.

[0020] At this time, preferably, the wire hole is formed in a long hole shape, and the long hole shape is a shape which gradually expands as it moves away from the pivot side. That is, the wire hole is formed to be smaller on the pivot side and becomes larger as it moves away from the pivot.

[0021] When thread is passed through the sewing needle and stitches are formed, the decorative thread is stretched through the thread hole formed in the arm of the thread puller. At this time, if the thread hole is formed to be smaller on the pivot side, the change in the tension position of the decorative thread can be reduced, and the occurrence of skipped stitches can be suppressed. On the other hand, since the thread hole is formed to be larger at a position away from the pivot side, the decorative thread can be easily passed through.

[0022] In addition, preferably, the wire puller is constructed as follows: the wire puller is composed of a pair of rotating parts with left-right symmetrical shapes including the main body, the cam groove and the arm, and both rotating parts are supported by the pivot so as to be freely rotatable, and the wire holes of the two parts move in opposite directions to each other as the cam follower moves with the advance and retreat of the slider.

[0023] Thus, the power transmission path to the pair of rotating parts constituting the wire puller is the same on the left and right, so even if there is a gap or wear in the movable part, the two rotating parts constituting the wire puller can perform symmetrical movements. Moreover, the drive mechanism can be extremely miniaturized and can be mounted even in a relatively small space such as a presser foot.

[0024] In addition, the present invention is characterized in that the presser foot comprises: a cloth pressing component, which abuts against the cloth on the needle plate; and a connecting component, which is arranged on the upper surface side of the cloth pressing component and connected to the presser foot leg, and the thread puller and the thread puller driving mechanism are arranged between the cloth pressing component and the connecting component.

[0025] By miniaturizing the thread puller, the thread puller and the thread puller driving mechanism can be arranged between the cloth pressing member and the connecting member. Thus, the thread puller driving mechanism is stored between the cloth pressing member and the connecting member, and can prevent contact with the operator's fingers when sewing.

[0026] In addition, the present invention is characterized in that the connecting rod mechanism comprises: a connecting rod part, which is longer in the up and down direction along the presser foot leg; and a swing support part, which is arranged on the presser foot leg between the upper end and the lower end of the connecting rod part to support the connecting rod part so as to swing freely, and the reciprocating motion of the reciprocating motion conversion mechanism is input from the upper end of the connecting rod part, and the reciprocating motion is output from the lower end of the connecting rod part toward the wire puller driving mechanism.

[0027] At this time, preferably, the presser foot leg includes: a link mechanism storage portion that stores the link mechanism; and a cover member that seals the link mechanism storage portion in a freely detachable manner, thereby hiding the link mechanism stored in the link mechanism storage portion.

[0028] Thus, the link mechanism is accommodated in the link mechanism accommodation portion of the presser leg, and the link mechanism accommodated in the link mechanism accommodation portion is hidden by the cover member, so that the movable parts are not exposed, safety is maintained, and the appearance can be improved.

[0029] In addition, the present invention is characterized in that the reciprocating motion conversion mechanism comprises: a cam, which rotates through an upper shaft; a yoke, which converts the rotation of the cam into a linear reciprocating motion; a transmission pin, which transmits the reciprocating motion of the yoke to the connecting rod mechanism; and a presser foot height detection body, which is used to keep the distance between the transmission pin and the fulcrum of the connecting rod mechanism constant, and the presser foot height detection body is supported by the frame of the sewing machine so as to be freely movable up and down, and connects the presser foot rod supporting the presser foot leg to the yoke.

[0030] When the thickness of the fabric changes during sewing, the height of the yoke needs to be adjusted accordingly. When the height of the yoke cannot be adjusted, the distance between the transfer pin and the fulcrum of the connecting rod mechanism cannot be kept constant, and the swing angle and range of the thread puller will change. Therefore, there is an undesirable situation that beautiful stitches cannot be formed stably. In contrast, according to the present invention, the yoke with the transfer pin and the presser foot rod are moved up and down integrally through the above-mentioned structure, so that even if the thickness of the fabric changes, beautiful stitches can be formed stably.

[0031] In addition, it can be constructed in the following manner: the yoke comprises: a base, which is provided with the transmission pin; and two wall portions, which are located in opposite directions across the rotating axis of the cam and are in contact with the cam, the base comprises a force-applying component, which supports the two wall portions respectively so as to be freely movable in the horizontal direction, and applies force to the two wall portions in the direction of approaching each other, and the two wall portions overcome the force of the force-applying component and move in the direction of moving away from each other, so as to release the power transmission from the reciprocating motion conversion mechanism to the connecting rod mechanism according to the rotational stopping force applied to the wire puller.

[0032] In the event that the wire puller comes into contact with a finger, or in the event that the wire upstream of the wire puller is entangled, an excessive load may be applied to the wire puller. According to the present invention, through the above-mentioned structure, when an excessive load is applied to the wire puller, the force-applying component that pulls the two walls together stretches, thereby limiting the drive of the wire puller. Therefore, in such a case, the function of releasing the driving force transmitted to the wire puller can be obtained, which can reduce the load on the wire puller and prevent the occurrence of malfunctions.

[0033] In addition, the present invention is characterized in that the connecting rod mechanism includes a connecting rod separation mechanism, which is connected to the reciprocating motion conversion mechanism by engaging with a part of the reciprocating motion conversion mechanism, and is separated from the reciprocating motion conversion mechanism by moving away from a part of the reciprocating motion conversion mechanism. The connecting rod separation mechanism includes: an operating rod that performs a separation operation; and a moving part that moves the connecting rod part in a direction of releasing the engagement with the reciprocating motion conversion mechanism via the swing support part through the separation operation of the operating rod.

[0034] Thus, the power can be turned on and off by a simple operation such as operating the operating lever. Furthermore, the power can be turned on and off regardless of the angle at which the main shaft of the sewing machine is located.

[0035] At this time, preferably, the moving member further moves the wire puller to a predetermined position along the forward and backward direction via the link member by the separation operation of the operating lever.

[0036] When the rod is continuously operated, the thread puller moves to a specified position along its forward and backward direction. When the power is cut off by operating the operating rod, the upper surface decorative seam is not performed. In this case, by moving the thread puller to a specified position (specifically, a position that does not interfere with the sewing operation), the sewing operation without performing the upper surface decorative seam can be smoothly performed. In addition, by setting the specified position to which the thread puller is moved as the position for performing the operation of passing the sewing thread through the thread puller, the threading operation through the thread puller can be smoothly performed.

[0037] In addition, the reciprocating motion conversion mechanism includes a transmission pin that is forced downward, and the connecting rod mechanism includes at the upper end of the connecting rod component: a recess that can be freely detachably engaged with the transmission pin; and an abutment surface that is continuously formed with the upper edge of one side of the recess and can allow the transmission pin to abut from above.

[0038] According to the above configuration, when the manual lever is operated in the reverse direction to start the upper decorative seam operation, the transmission pin slides along the contact surface toward the recess of the link mechanism, and the transmission pin can be reliably fitted into the recess. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is an explanatory perspective view showing the main part of the sewing machine according to the embodiment of the present invention.

[0040] Figure 2 It is an explanatory perspective view showing the appearance of a presser foot.

[0041] Figure 3 is an explanatory top view showing a wire puller and a wire puller driving mechanism.

[0042] Figure 4 is an illustrative side view of a presser foot and presser leg.

[0043] Figure 5 is an explanatory side view showing the structure of the link mechanism.

[0044] Figure 6 It is an explanatory diagram of the main part of the link mechanism showing a state of being connected to the transmission pin.

[0045] Figure 7 It is an explanatory diagram showing the operation of the link release mechanism.

[0046] Figure 8 It is an explanatory diagram showing a schematic structure when the reciprocating motion conversion mechanism is viewed from the side.

[0047] Fig. 9 It is an explanatory perspective view showing a schematic structure of a reciprocating motion conversion mechanism. DETAILED DESCRIPTION

[0048] An embodiment of the present invention will be described based on the accompanying drawings. This embodiment is a sewing machine for performing decorative seams on the upper surface of a cloth. Figure 1 As shown in the main part, the sewing machine of this embodiment comprises: a thread puller 3, which is arranged on a cloth pressing member 2 provided on a presser foot 1; and a thread puller driving mechanism 4 (refer to Figure 3 ), which drives the wire puller 3.

[0049] To the wire puller driving mechanism 4 , the driving force of the upper shaft 7 is transmitted via the reciprocating motion conversion mechanism 5 and the link mechanism 6 .

[0050] exist Figure 1 In the figure, for the convenience of explanation, the reciprocating motion conversion mechanism 5 and the connecting rod mechanism 6 are shown in an exposed state, but the reciprocating motion conversion mechanism 5 is accommodated inside the sewing machine housing which is omitted from the figure, and the connecting rod mechanism 6 is accommodated inside the presser foot leg 8 as described later. The presser foot 1 is connected to the presser foot rod 9 extending up and down via the presser foot leg 8.

[0051] Figure 2 1 shows a presser foot 1. A thread puller 3 is provided on the presser foot 1. Figure 3 As shown, the wire puller 3 is composed of a pair of rotating parts 3a and 3b formed of metal plates. The two rotating parts 3a and 3b are symmetrical in shape, but are supported by a pivot 10 so as to be freely rotatable in a manner that a part overlaps in the vertical direction. The pivot 10 is set on the presser foot 1 and coaxially supports the two rotating parts 3a and 3b.

[0052] Each of the rotating members 3 a and 3 b includes a main body 11 through which the pivot shaft 10 passes, a curved long hole-shaped cam groove 12 formed in the main body 11 , and an arm 13 extending from the main body 11 .

[0053] A wire hole 14 is formed at the tip of the arm 13. The wire hole 14 is in the shape of an elongated hole extending toward the pivot 10, and the elongated hole gradually expands as it moves away from the pivot 10.

[0054] That is, when the approach direction of the two arms 13 is set to the inner side and the distance direction is set to the outer side, the wire hole 14 is formed into a shape in which the small diameter hole portion 14a located on the inner side (the side of the pivot 10) and the large diameter hole portion 14b located on the outer side (the side away from the pivot 10) are continuous with each other.

[0055] The thread (decorative thread) for implementing the decorative stitch is passed through the thread hole 14. By providing the large-diameter hole portion 14b in the thread hole 14, the threading operation of the decorative thread becomes easier. In addition, by providing the small-diameter hole portion 14a in the thread hole 14, the change in the tension position of the decorative thread during the rotation of the thread puller 3 can be reduced, and the occurrence of skipped stitches can be suppressed.

[0056] like Figure 3 As shown, the wire puller driving mechanism 4 has a slider 15 and a cam follower 16. The slider 15 is located between the upper and lower rotating parts 3a and 3b constituting the wire puller 3, and is configured to be freely movable in the front and rear directions along the feeding direction of the fabric. The cam follower 16 is provided on the surface and back of the slider 15, and slides along the cam groove 12 of each rotating part 3a and 3b.

[0057] When the cam follower 16 slides along the curvature of the cam groove 12 as the slider 15 moves, the rotating parts 3a, 3b of the wire puller 3 supported by the pivot 10 so as to be freely rotatable rotate in opposite directions to each other. Thus, according to the moving direction of the slider 15, the two arms 13 of the wire puller 3 move in a manner of approaching or moving away.

[0058] like Figure 1 and Figure 2 As shown, the presser foot 1 comprises: a cloth pressing member 2, which abuts against the cloth (not shown) on the needle plate 18 near the sewing needle 17 to press; and a connecting member 19, which is arranged on the upper surface side of the cloth pressing member 2 and connected to the presser foot leg 8.

[0059] like Figure 2 As shown, the thread puller driving mechanism 4 is housed between the cloth pressing member 2 of the presser foot 1 and the connecting member 19. In addition to the arm 13, the thread puller 3 is also housed between the cloth pressing member 2 and the connecting member 19 together with the thread puller driving mechanism 4. Thus, when sewing, the operator or the cloth piece can be prevented from accidentally contacting the thread puller 3 and the thread puller driving mechanism 4.

[0060] like Figure 1 and Figure 3 As shown, the slider 15 of the wire puller driving mechanism 4 is connected to the link mechanism 6. The link mechanism 6 transmits the reciprocating motion generated by the reciprocating motion conversion mechanism 5 to the slider 15 of the wire puller driving mechanism 4. The reciprocating motion conversion mechanism 5 converts the rotation of the upper shaft 7 into a reciprocating motion.

[0061] like Figure 1 and Figure 5 As shown, the link mechanism 6 comprises: a link component 20 extending up and down; a swing support portion 21, which supports the link component 20 so that it can swing freely; and an advance and retreat component 22 connected to the lower end of the link component 20. The link mechanism 6 is housed in a link mechanism housing portion 23 of the presser foot leg 8.

[0062] Moreover, the link mechanism 6 is stored in the link mechanism storage portion 23 of the presser foot leg 8. Figure 4 As shown, the cover member 24 is covered and hidden inside the presser foot leg 8. Thus, the link mechanism 6 is prevented from being contacted from the outside, and the mechanical part is not exposed, and the appearance is good.

[0063] like Figure 5 As shown, the advancing and retreating member 22 is connected to the slider 15 of the wire puller driving mechanism 4, and converts the swing of the link member 20 into an advancing and retreating motion to drive the slider 15.

[0064] An upper connecting portion 25 connected to the reciprocating motion conversion mechanism 5 is provided at the upper end of the link member 20. The upper connecting portion 25 is connected by a link disconnecting mechanism 26 so as to be detachable.

[0065] like Figure 6 and Figure 7 As shown, a recess 27 and a contact surface 28 are formed on the upper connecting portion 25. The recess 27 is engaged with a transmission pin 29 of the reciprocating motion conversion mechanism 5 described later. The contact surface 28 is formed continuously with one upper edge of the recess 27.

[0066] like Figure 5 As shown in FIG. 1 , a support shaft 30 is provided on the swing support portion 21, and the support shaft 30 serves as a swing fulcrum of the link member 20. In addition, the swing support portion 21, as a moving member in the present invention, also serves as a part of the structure of the link release mechanism 26. That is, the link release mechanism 26 includes: a pressing pin 31, which is provided on the swing support portion 21; and an operating lever 32, which performs a rotation operation on the swing support portion 21.

[0067] When performing surface decorative seam operations, Figure 6As shown, the operating rod 32 is lifted (to a horizontal state). When the operating rod 32 is lifted, the transmission pin 29 engages with the recess 27 of the connecting rod member 20, and the pressing pin 31 is located at the second position 34 that does not interfere with the connecting rod member 20 and becomes a retracted state. When the surface decorative seam operation is performed in this state, the transmission pin 29 of the reciprocating motion conversion mechanism 5 causes the connecting rod member 20 to swing, thereby driving the slider 15 of the wire puller driving mechanism 4 via the advance and retreat member 22 to rotate the wire puller 3.

[0068] When no decorative seam work is performed, Figure 7 As shown, the operating rod 32 is lowered. When the operating rod 32 is lowered, as shown Figure 7 As shown by the dotted line, the support shaft 30 of the swing support portion 21 moves downward, and the link member 20 moves downward. At the same time, the pressing pin 31 presses the link member 20 at the first position 33, and the link member 20 rotates clockwise around the support shaft 30.

[0069] As a result, the transmission pin 29 is released from the recessed portion 27 of the link member 20, and the reciprocating motion conversion mechanism 5 is separated from the link mechanism 6. When the pressing pin 31 moves to the first position 33, the advancing and retreating member 22 moves to the retreated position and stops.

[0070] At this time, the transmission pin 29 that has escaped from the recessed portion 27 is located above the contact surface 28. Furthermore, by fixing the advancing and retreating member 22 in the retreated position, the slider 15 moves the two arm portions 13 of the wire puller 3 away from each other and maintains this state.

[0071] When the operating lever 32 is lifted from the lowered state, the pressing pin 31 moves to the second position 34, and the link member 20 becomes a freely swingable state. At the same time, the support shaft 30 is displaced upward, so that the link member 20 moves upward, and the transmission pin 29 abuts against the abutment surface 28 of the link member 20. At this time, the link member 20 pushes up the transmission pin 29, but the transmission pin 29 is urged downward by the tension spring 54 of the presser foot height detection body 44 described later, so it moves upward together with the link member 20.

[0072] When sewing operation starts, the reciprocating motion conversion mechanism 5 starts reciprocating motion, and accordingly, the transmission pin 29 slides on the contact surface 28 and fits into the recess 27. Thus, the reciprocating motion conversion mechanism 5 and the link mechanism 6 are connected, and sewing operation can be started smoothly.

[0073] like Figure 8 As shown, the reciprocating motion conversion mechanism 5 includes a cam 35 and a yoke 36. A cam shaft 37 is fixed to a mounting plate 38. The cam 35 and a driven gear 40 are supported on the cam shaft 37. The cam 35 and the driven gear 40 are formed integrally. Figure 1As shown, the driven gear 40 meshes with the driving gear 39 of the upper shaft 7, decelerating the rotation of the upper shaft 7 and rotating the cam 35.

[0074] like Figure 8 and Fig. 9 As shown, the yoke 36 includes a base 41, a pair of cam abutment members (a first cam abutment member 42 and a second cam abutment member 43), and a presser foot height detection body 44. The base 41 includes a transmission pin 29 for connecting with the link mechanism 6.

[0075] The first cam contact member 42 includes a first wall portion 45 that contacts the cam 35, and the second cam contact member 43 includes a second wall portion 46 that faces the first wall portion 45 and contacts the cam 35. When the cam 35 rotates and moves the first cam contact member 42 via the first wall portion 45, the base 41 moves to one side. When the cam 35 rotates and moves the second cam contact member 43 via the second wall portion 46, the base 41 moves to the other side.

[0076] The first cam abutment member 42 and the second cam abutment member 43 are movable in directions away from each other, and are connected via a tension spring 47 that is a biasing means that biases the first cam abutment member 42 and the second cam abutment member 43 in directions toward each other.

[0077] When the interval between the first wall portion 45 and the second wall portion 46 is a predetermined interval (minimum interval), the tension spring 47 fixes the first cam abutment member 42 and the second cam abutment member 43 to the base portion 41 by its urging force.

[0078] The base 41 is composed of a first moving member 48 and a second moving member 49. The first moving member 48 is provided with a transmission pin 29, and the presser height detector 44 is connected to the second moving member 49. The base 41 is supported by the mounting plate 38 so as to be movable in the lateral and vertical directions.

[0079] That is, the second movable member 49 has a pair of connecting pins 50. The two connecting pins 50 penetrate the mounting plate 38 and are connected to the first movable member 48. The mounting plate 38 has a pair of longitudinal holes 51, and the first movable member 48 has a pair of transverse holes 52 extending in a direction orthogonal to the longitudinal holes 51 of the mounting plate 38. The connecting pin 50 extending from the second movable member 49 penetrates the longitudinal holes 51 of the mounting plate 38 and penetrates the transverse holes 52 of the first movable member 48.

[0080] Thus, when the cam 35 rotates, the first cam abutment member 42 and the second cam abutment member 43 are alternately pressed, and the first movable member 48 reciprocates in the horizontal direction. At this time, the first movable member 48 reciprocates relative to the connecting pin 50 located at a fixed position via the horizontal long hole 52. In addition, when the presser foot height detection body 44 moves in the up-down direction, the connecting pin 50 is guided by the vertical long hole 51 of the mounting plate 38, so that the second movable member 49 and the first movable member 48 move in the up-down direction together.

[0081] The presser foot height detection body 44 moves up and down following the up and down movement of the presser foot rod 9 supporting the presser foot leg 8. That is, the presser foot height detection body 44 has a connecting claw piece 53 and is urged downward by a tension spring 54. A contact component 55 is fixedly provided on the presser foot rod 9, and the contact component 55 makes the connecting claw piece 53 contact its upper surface.

[0082] When the presser foot lever 9 moves upward, the contact member 55 pushes up the connecting claw piece 53 against the biasing force of the tension spring 54, and the presser foot height detection body 44 moves upward. As the presser foot height detection body 44 moves upward, the yoke 36 moves upward.

[0083] On the other hand, when the presser bar 9 moves downward, the contact between the connecting claw 53 and the contact member 55 is maintained by the biasing force of the tension spring 54, so that the presser height detector 44 moves downward. When the presser height detector 44 moves downward, the yoke 36 moves downward.

[0084] Furthermore, for example, when the thickness of the fabric increases during sewing, the link mechanism 6 moves upward together with the presser foot leg 8, so that the distance between the transmission pin 29 and the support shaft 30 of the link member 20 decreases, and the rotation angle of the thread puller 3 increases.

[0085] Therefore, in the present embodiment, the up-and-down movement of the presser foot rod 9 supporting the presser foot leg 8 is transmitted to the yoke 36 through the presser foot height detector 44 through the above-mentioned structure. Thus, even if the thickness of the cloth changes during sewing, the position of the yoke 36 relative to the presser foot leg 8 does not change, thereby preventing the distance between the transmission pin 29 and the support shaft 30 of the link member 20 from changing.

[0086] Therefore, even if the thickness of the fabric changes during sewing, the reciprocating motion conversion mechanism 5 of the above structure can transmit accurate reciprocating motion to the thread puller 3 without being affected by the change, so that sewing can be performed without pause.

[0087] In addition, if Figure 1As shown, the thread puller 3 rotates by the reciprocating motion transmitted from the reciprocating motion conversion mechanism 5 to the thread puller driving mechanism 4 via the connecting rod mechanism 6. However, for example, when an operator performing sewing operations comes into contact with the rotating thread puller 3 and an external force is applied to the thread puller 3 to stop the rotation, damage may occur to various parts or the smooth rotation of the upper shaft 7 may be hindered.

[0088] Therefore, if Figure 8 As shown, the reciprocating motion conversion mechanism 5 has a protection function when the wire puller 3 stops unexpectedly. That is, as described above, the yoke 36 is configured so that the first cam abutment member 42 and the second cam abutment member 43 can move away from each other, and the two are urged toward each other by the tension spring 47.

[0089] The protective function is specifically described. For example, when an operator in sewing operation contacts the thread puller 3, the thread puller 3 attempts to stop. On the other hand, the driving force transmitted from the cam 35 of the reciprocating motion conversion mechanism 5 to the yoke 36 attempts to rotate the thread puller 3 via the connecting rod mechanism 6 and the thread puller drive mechanism 4. When such opposing forces are applied to the thread puller 3, the thread puller drive mechanism 4, the connecting rod mechanism 6 and the reciprocating motion conversion mechanism 5, excessive load may be applied to any part and damage the part.

[0090] In contrast, in the reciprocating motion conversion mechanism 5 of the present embodiment, when a force is applied to stop the reciprocating motion of the base 41 via the connecting rod mechanism 6, only the first cam abutment component 42 pressed by the cam 35 overcomes the force of the tension spring 47 and moves in a direction away from the second cam abutment component 43, or only the second cam abutment component 43 pressed by the cam 35 overcomes the force of the tension spring 47 and moves in a direction away from the first cam abutment component 42, causing the cam 35 to idle and no reciprocating motion to occur in the base 41.

[0091] Thus, even if the thread puller 3 stops rotating during sewing, the rotation of the cam 35 is not transmitted to the base 41 of the yoke 36, so that damage to each part can be prevented.

[0092] In addition, in the above-mentioned embodiment, an example is shown in which the two rotating parts 3a and 3b of the wire puller 3 are made into a left-right symmetrical shape and the two rotating parts 3a and 3b are coaxially supported by a pivot 10, but it is not limited to this. Although not shown in the figure, the rotating parts of the wire puller can also be of different shapes. In addition, two pivots can be provided and the rotating parts can be supported by different pivots.

[0093] [Explanation of symbols]

[0094] 1: presser foot; 2: cloth pressing part; 3: thread puller; 3a, 3b: rotating parts; 4: thread puller driving mechanism; 5: reciprocating motion conversion mechanism; 6: connecting rod mechanism; 7: upper shaft; 8: presser foot leg; 9: presser foot rod; 10: pivot; 11: main body; 12: cam groove; 13: arm; 14: thread hole; 15: slider; 16: cam follower; 19: connecting part; 20: connecting rod part; 21: swing Dynamic supporting part (moving part); 23: connecting rod mechanism storage part; 24: cover part; 26: connecting rod separation mechanism; 27: recessed part; 28: abutment surface; 29: transmission pin; 30: support shaft (fulcrum); 32: operating lever; 35: cam; 36: yoke; 41: base; 44: presser foot height detection body; 45: first wall part (wall part); 46: second wall part (wall part); 47: tension spring (force-applying part).

Claims

1. A sewing machine for forming decorative stitches on the upper surface of a cloth, characterized in that: have: A presser foot, which is adjacent to the sewing needle that moves up and down to press the cloth on the needle plate; a presser foot leg, which supports the presser foot; a thread puller, which has a thread hole for the sewing thread to pass through up and down and can rotate freely; a thread puller driving mechanism, which drives the thread puller to rotate; a reciprocating motion conversion mechanism, which is located above the needle plate and converts the rotation of the upper shaft into a linear reciprocating motion in the front and rear directions; and a connecting rod mechanism, which transmits the reciprocating motion generated by the reciprocating motion conversion mechanism to the thread puller driving mechanism, The wire puller and the wire puller driving mechanism are both arranged on the presser foot, and the connecting rod mechanism is arranged on the presser foot leg.

2. The sewing machine according to claim 1, characterized in that: The presser foot has a pivot, which is located further back than the sewing needle and extends up and down. The wire puller comprises: a main body supported by the pivot; a cam groove formed on the main body and bent along the rotation track; and an arm extending forward from the main body and having the wire hole formed therein. The wire puller driving mechanism comprises: a slider, which moves forward and backward toward the pivot by the reciprocating motion transmitted from the reciprocating motion conversion mechanism via the connecting rod mechanism; and a cam follower, which is arranged on the slider and slides along the cam groove of the wire puller as the slider moves, thereby rotating the wire puller.

3. The sewing machine according to claim 2, characterized in that: The wire hole is formed in a long hole shape which gradually expands as it moves away from the pivot side.

4. The sewing machine according to claim 2, characterized in that: The wire puller is composed of a pair of rotating parts with left-right symmetrical shapes including the main body, the cam groove and the arm. Both rotating parts are supported by the pivot so as to be freely rotatable. The cam follower moves with the advance and retreat of the slider, and the wire holes of the two parts move in opposite directions.

5. The sewing machine according to claim 1, characterized in that: The presser foot comprises: a cloth pressing member that contacts the cloth on the needle plate; and a connecting member that is arranged on the upper surface side of the cloth pressing member and connected to the presser foot leg. The wire puller and the wire puller driving mechanism are arranged between the cloth pressing component and the connecting component.

6. The sewing machine according to claim 1, characterized in that The link mechanism comprises: a link member which is long in the vertical direction along the presser leg; and a swing support portion which is provided on the presser leg between the upper end and the lower end of the link member to support the link member so that it can swing freely. The reciprocating motion of the reciprocating motion conversion mechanism is input from the upper end of the link member, and the reciprocating motion is output from the lower end of the link member toward the wire puller driving mechanism.

7. The sewing machine according to claim 6, characterized in that The presser foot leg includes: a link mechanism storage portion that stores the link mechanism; and a cover member that detachably seals the link mechanism storage portion, thereby hiding the link mechanism stored in the link mechanism storage portion.

8. The sewing machine according to claim 1, characterized in that The reciprocating motion conversion mechanism comprises: a cam that rotates via an upper shaft; a yoke that converts the rotation of the cam into a linear reciprocating motion; a transmission pin that transmits the reciprocating motion of the yoke to the link mechanism; and a presser foot height detection body that is used to keep a distance between the transmission pin and a fulcrum of the link mechanism constant. The presser foot height detection body is supported by the frame of the sewing machine so as to be freely movable up and down, and connects the presser foot rod supporting the presser foot leg to the yoke.

9. The sewing machine according to claim 8, characterized in that The yoke includes: a base portion provided with the transmission pin; and two wall portions located in opposing directions across the rotation axis of the cam and in contact with the cam. The base portion includes a biasing member that supports the two wall portions so as to be freely movable in the horizontal direction and biases the two wall portions in a direction toward each other. The two wall portions move in directions away from each other against the urging force of the urging member so as to release the power transmission from the reciprocating motion conversion mechanism to the link mechanism according to the rotation stopping force applied to the wire puller.

10. The sewing machine according to claim 6, characterized in that The link mechanism includes a link separation mechanism, which is connected to the reciprocating motion conversion mechanism by engaging with a part of the reciprocating motion conversion mechanism and is separated from the reciprocating motion conversion mechanism by moving away from a part of the reciprocating motion conversion mechanism. The link release mechanism includes an operating lever that performs a release operation, and a moving member that moves the link member in a direction of releasing engagement with the reciprocating motion conversion mechanism via the swing support portion in response to the release operation of the operating lever.

11. The sewing machine according to claim 10, characterized in that The moving member further moves the wire puller to a predetermined position along the forward and backward direction via the link member by the separation operation of the operating lever.

12. The sewing machine according to claim 11, characterized in that The reciprocating motion conversion mechanism includes a transmission pin which is urged downward. The link mechanism includes, at an upper end portion of the link member, a recessed portion detachably engaged with the transmission pin, and an abutting surface formed continuously with an upper edge of one side of the recessed portion and capable of being abutted by the transmission pin from above.

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