JP2014147539A - Sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sewing machine which can reliably and independently operate a mechanism for releasing tension applied by a main thread tension unit and a mechanism for switching the state of a sub thread tension unit applying tension.SOLUTION: During sewing, a main thread tension unit 110 applies tension to a needle thread, and a sub thread tension unit 130 releases the application of tension to the needle thread. When the thread is cut, a wire 195 connected to a thread cutting solenoid for driving a thread cutting mechanism pulls a hook part 168. A first arm part 160 turns clockwise with a support shaft 152 as a fulcrum and presses a releasing pin 120 by a first cam surface 167, thereby releasing the application of tension to the needle thread by the main thread tension unit 110. In conjunction with this, a second arm part 170 turns counterclockwise with a support shaft 153 as a fulcrum and releases the pressing of a switching pin 140 by a second cam surface 177, thereby allowing the sub thread tension unit 130 to apply tension to the needle thread.

Description

  The present invention relates to a sewing machine including a main thread tension device and a sub-thread tension device that apply tension to an upper thread.

  The sewing machine includes a head portion and a bed portion. A needle bar that moves in the vertical direction is provided inside the head. A shuttle that rotates in cooperation with the needle bar is provided inside the bed. The needle bar attaches a sewing needle to the lower end and supplies the upper thread. The hook accommodates a bobbin wound with a lower thread, supplies the lower thread from the bobbin, and entangles with the upper thread to form a seam on the work cloth. The upper thread is supplied from the thread spool and is passed through the eye of the sewing needle through a secondary thread tensioner, a main thread tensioner, a thread take-up spring, a thread guide, a balance, a thread guide, and the like provided on the head. The main thread tensioner applies tension necessary for sewing to the upper thread during sewing. The secondary thread tensioner applies tension necessary for cutting the upper thread at the time of thread trimming. The main thread tensioner releases the tension applied to the upper thread during thread trimming.

  The main thread tension adjuster adjusts the magnitude of tension applied to the upper thread during sewing according to the type of work cloth. At the time of sewing, the magnitude of the tension applied to the upper thread by the main thread tensioner is larger than the tension applied to the upper thread by the secondary thread tensioner. The sewing machine needs to reduce the tension applied to the upper thread when sewing a thin cloth or the like. If the secondary thread tensioner is adjusted in accordance with the magnitude of the tension applied by the main thread tensioner, the secondary thread tensioner may not be able to apply an appropriate tension to the upper thread during thread trimming. Therefore, there is a possibility that the remaining yarn length after cutting becomes unstable. The sewing machine described in Patent Document 1 releases the tension applied to the upper thread by the main thread tensioner at the time of thread trimming, and drives the secondary thread tensioner that was in the released state at the time of sewing to apply tension to the upper thread. Switch to state. Therefore, the main thread tension device and the auxiliary thread tension device act on the upper thread independently at the time of sewing and thread trimming, respectively, so that tension at the time of sewing and thread trimming can be appropriately applied.

Japanese Patent Laid-Open No. 11-244565

  However, the sewing machine disclosed in Patent Document 1 is a mechanism in which a mechanism for releasing the application of tension by the main thread tensioner and a mechanism for switching the tension application state by the auxiliary thread tensioner are independent of each other, and operates by different driving sources. The sewing machine performs electrical control to synchronize the operation of the main thread tensioner and the operation of the secondary thread tensioner. Therefore, if any one of the drive sources breaks down and synchronization is lost, the sewing machine may perform a thread trimming operation in a state in which an appropriate tension is not applied to the upper thread. The upper thread remains without being cut and may get entangled with the thread trimmer.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and is a sewing machine that can reliably and independently operate a release mechanism for releasing tension applied to a main thread tensioner and a mechanism for switching tension applied to a secondary thread tensioner. The purpose is to provide.

  According to the sewing machine according to the first aspect of the present invention, a sewing needle that passes through the upper thread and moves up and down by the rotation of the main shaft, a balance that moves up and down in conjunction with the vertical movement of the sewing needle, and an upper thread that is higher than the scale. In a sewing machine that is provided upstream of the supply path and includes a thread tension mechanism that can apply tension to the upper thread, the thread tension mechanism includes a first thread tensioner and an upper thread that is higher than the first thread tensioner. A second thread tensioner positioned upstream of the supply path, a release mechanism for releasing the tension applied to the upper thread by the first thread tensioner, and a tension applied to the upper thread by the second thread tensioner. A sewing machine is provided that includes a switching mechanism that switches from a released state to an assignable state, and a drive mechanism that drives the releasing mechanism and the switching mechanism in synchronization.

  In the first aspect, at the time of sewing, the first thread tensioner applies tension to the upper thread, and the second thread tensioner releases tension applied to the upper thread. The upper thread can obtain a proper tension from the first thread tensioner and form a seam together with the lower thread. During thread trimming, the drive mechanism drives the release mechanism and the switching mechanism in synchronization. The first thread tensioner releases the tension applied to the upper thread, and the second thread tensioner applies tension to the upper thread. Accordingly, the sewing machine can cut the upper thread with an appropriate tension from the second thread tensioner. The drive mechanism mechanically drives the release mechanism and the switching mechanism. Therefore, the release mechanism and the switching mechanism can operate reliably without being out of synchronization.

  A sewing machine according to a first aspect includes a thread trimming mechanism that cuts an upper thread, a power source that applies power to drive the thread trimming mechanism, and a transmission member that transmits power to the drive mechanism, The transmission member may be connected to the power source. At the time of thread trimming, the sewing machine can drive the thread trimming mechanism via the power source and operate the release mechanism and the switching mechanism by the driving mechanism in conjunction with each other.

  The drive mechanism of the sewing machine according to the first aspect is supported by a sewing machine frame so that one end of the drive mechanism is closer to the release mechanism than the switching mechanism, and the release mechanism slides on the one end. A first arm portion having a first cam surface and one end portion are rotatably supported by the sewing machine frame at a position closer to the switching mechanism than the release mechanism, and the switching mechanism slides on the one end portion. A second arm portion having a second cam surface, a support portion for rotatably supporting the other end portion of the first arm portion and the other end portion of the second arm portion, and the first A connecting portion that is provided at a position closer to the one end portion than the support portion on the other end portion side of the arm portion and connected to the transmission member may be provided. In this case, the power source rotates the first arm portion and the second arm portion by moving the position of the support portion via the transmission member, and the first cam surface and the second arm portion are rotated. The release mechanism and the switching mechanism that slide on the second cam surface may be driven.

  By driving the drive mechanism with the power transmitted from one power source, the sewing machine can reduce the configuration of the present application. Since the sewing machine drives the drive mechanism with one power source, there is no deviation in the synchronization timing, and it is possible to accurately release the tension at the time of sewing and apply the tension at the time of cutting to the upper thread. Since the first arm portion and the second arm portion are supported by the support portion and rotate in conjunction with the drive mechanism, power can be reliably transmitted to the release mechanism and the switching mechanism in a synchronized manner. The sewing machine synchronizes the sliding of the release mechanism with the first cam surface and the sliding of the switching mechanism with the second cam surface. Therefore, the sewing machine can temporarily and simultaneously cause a state in which the application of tension by the first thread tensioner is released and a state in which the application of tension by the second thread tensioner is released. The sewing machine can apply the tension at the time of thread trimming to the upper thread after reducing the tension at the time of sewing remaining on the upper thread at the time of thread trimming. Therefore, the sewing machine cuts the upper thread in an excessively stretched state, and can suppress variations in the remaining thread length of the upper thread to the sewing needle.

  In the sewing machine according to the first aspect, the first cam surface and the second cam surface are moved to the first cam surface rather than sliding of the switching mechanism to the second cam surface when the power source is driven. Each of the release mechanisms may have a cam surface on which sliding is first performed. The sewing machine creates a state in which the tension from both thread tensioners is not applied to the upper thread or the tension is reduced. Accordingly, the sewing machine can apply the tension at the time of thread trimming after releasing the tension remaining on the thread after sewing. When the thread is trimmed while the tension at the time of sewing remains, there is a possibility that the thread jumps after the thread is trimmed and the thread is pulled out from the sewing needle. By releasing the tension at the time of sewing as described above, the sewing machine can prevent the thread from coming off.

  The sewing machine according to the first aspect is provided in the first thread tensioner, and the power is transmitted by the thread take-up spring that swings up and down with the movement of the upper thread by the vertical movement of the balance and the release mechanism, and the thread take-up You may further provide the control mechanism which controls the rocking | fluctuation to the up-and-down of a spring. Along with the release of the tension to the upper thread by the first thread tensioner by the release mechanism, the restriction mechanism is operated by the release mechanism to restrict the swing of the thread take-up spring. The sewing machine can prevent the thread take-up spring from swinging when the upper thread is cut and the amount of yarn remaining on the upper thread from being cut off varies.

1 is a perspective view of a sewing machine 1. FIG. FIG. 3 is an enlarged perspective view of the vicinity of the head 5 of the sewing machine 1. 2 is a perspective view of a thread tension mechanism 100. FIG. 3 is a left side view of the thread tension mechanism 100. FIG. 3 is a front view of the yarn release link mechanism 150. FIG. 3 is a rear view of the yarn release link mechanism 150. FIG. 7 is a perspective view of a restriction mechanism 180. FIG. FIG. 6 is a front view of the yarn release link mechanism 150 when operating. FIG. 6 is a perspective view when the yarn release link mechanism 150 is activated. It is a timing diagram which shows the ON / OFF timing of the solenoid at the time of thread trimming.

  Hereinafter, a sewing machine 1 according to an embodiment of the present invention will be described with reference to the drawings. The schematic structure of the sewing machine 1 will be described with reference to FIG. 1 are the left side, right side, front side, rear side, upper side, and lower side of the sewing machine 1, respectively.

  As shown in FIG. 1, the sewing machine 1 includes a bed portion 2, a pedestal portion 3, an arm portion 4, and a head portion 5. The bed portion 2 extends in the left-right direction, and includes a lower shaft 21, a shuttle mechanism 80, a thread trimming mechanism 20, and the like. The pedestal 3 extends upward from the right end side of the bed 2 and includes a timing belt 31, a sewing machine motor 32, and the like. The arm portion 4 extends to the left from the upper side of the pillar portion 3 so as to face the upper surface of the bed portion 2 and includes a main shaft 41 and the like inside. The sewing machine motor 32 rotates clockwise when the main shaft 41 is viewed from the left.

  The arm part 4 includes a head part 5 on the left side. The head 5 includes a balance driving mechanism 50, a needle bar driving mechanism 10, a thread tension mechanism 100 (see FIG. 3) described later, and the like. The main shaft 41 has a right end connected to the sewing machine motor 32 and a left end connected to a needle bar vertical movement mechanism (not shown). The main shaft 41 transmits the rotational force accompanying the driving of the sewing machine motor 32 to the balance driving mechanism 50 via the needle bar vertical movement mechanism, and drives the balance driving mechanism 50. The balance drive mechanism 50 includes a balance 51 that moves up and down during sewing to pull up the upper thread. The balance drive mechanism 50 connects the needle bar drive mechanism 10 on the left side.

  The needle bar drive mechanism 10 includes a needle bar 11, needle bar support cylinders 12 and 13, a needle bar holder 14, and the like. The needle bar support cylinders 12 and 13 are fixed to a sewing machine frame (not shown). The needle bar support cylinders 12 and 13 support the upper and lower parts of the needle bar 11, respectively, and guide the movement of the needle bar 11 in the vertical direction. The needle bar holder 14 holds the needle bar 11 at a position between the needle bar support cylinder 12 and the needle bar support cylinder 13. The needle bar holder 14 is connected to the needle bar vertical movement mechanism via the balance drive mechanism 50, and the driving force accompanying the rotation of the main shaft 41 is transmitted via the needle bar vertical movement mechanism. The needle bar holder 14 is driven in conjunction with the balance 51 to move the needle bar 11 up and down. The lower end side of the needle bar 11 is exposed from the lower side of the head 5 and extends downward. The needle bar 11 has a sewing needle 7 attached to the lower end.

  The lower shaft 21 extends in the left-right direction and includes a pulley 23 at the right end. The main shaft 41 includes a pulley 42 at a position corresponding to the position of the pulley 23 of the lower shaft 21. The pulley 42 and the pulley 23 are connected via the timing belt 31. When the main shaft 41 rotates as the sewing machine motor 32 is driven, the lower shaft 21 rotates clockwise as viewed from the left via the timing belt 31. The lower shaft 21 includes a lower shaft gear 22 on the left side of the pulley 23.

  The shuttle mechanism 80 includes a shuttle shaft 81 extending in the left-right direction. The hook shaft 81 is disposed in parallel with the lower shaft 21 and includes a hook shaft gear 84 at the right end. The hook shaft gear 84 meshes with the lower shaft gear 22 of the lower shaft 21. The shuttle shaft 81 is driven by the lower shaft 21 that rotates as the sewing machine motor 32 is driven, and rotates counterclockwise as viewed from the left.

  The hook shaft 81 has a rotary hook 8 at the left end. The rotary hook 8 rotates together with the hook shaft 81. The rotary hook 8 is equipped with a bobbin case 82 that houses a bobbin (not shown) around which a lower thread is wound. The rotary hook 8 is positioned below a needle plate (not shown) provided on the upper portion of the bed portion 2. The needle bar 11 is located immediately above the needle plate. When the needle bar 11 is lowered during sewing, the lower end of the sewing needle 7 passes through a needle hole (not shown) opened in the needle plate and reaches the rotary hook 8. The rotary hook 8 cooperates with the needle bar 11 and entangles the lower thread drawn from the bobbin case 82 with the upper thread held by the sewing needle 7. The balance 51 pulls the upper thread entangled with the lower thread onto the needle plate and forms a seam on the work cloth.

  The thread trimming mechanism 90 is located above the hook mechanism 80 and near the needle hole of the needle plate. The thread trimming mechanism 90 includes a moving blade (not shown) and a fixed blade (not shown). The moving blade is rotatable along the outer periphery of the rotary hook 8. The thread trimming mechanism 90 is driven by driving a thread trimming solenoid 190 (see FIG. 3). The thread trimming solenoid 190 is driven when a thread trimming signal is input. When the thread trimming solenoid 190 is driven, a thread trimming cam (not shown) is activated. The thread trimmer cam transmits the driving force of the hook shaft 81 to the moving blade. The moving blade is cut by sandwiching the upper thread with the fixed blade. Details of the thread trimmer solenoid 190 will be described later.

  Next, the configuration of the thread tension mechanism 100 will be described with reference to FIGS. As shown in FIGS. 2 and 3, the thread tension mechanism 100 includes a main thread tensioner 110, a subsidiary thread tensioner 130, a release pin 120, a switching pin 140, and a thread release link mechanism 150. The main thread tensioner 110 and the secondary thread tensioner 130 are fixed to the sewing machine frame so as to be exposed on the front surface of the head 5. The main thread tensioner 110 is located at the lower part of the front surface of the head 5. The main thread tensioner 110 is a device that applies tension to the upper thread mainly during sewing. The secondary thread tensioner 130 is located in the upper part of the front surface of the head 5. The secondary thread tensioner 130 is a device that applies tension to the upper thread mainly during thread trimming.

  The main thread tensioner 110 and the secondary thread tensioner 130 constitute a part of a supply path for supplying the upper thread wound around the thread spool 6 to the sewing needle 7 attached to the needle bar 11. The secondary thread tensioner 130 is located upstream of the main thread tensioner 110 in the supply path. The supply path includes a thread guide 43, a secondary thread tensioner 130, a main thread tensioner 110, a thread hook 55, a thread guide 56, a balance 51, and thread guides 57, 58, and 59. The yarn guide 43 protrudes upward on the upper surface of the arm portion 4 and guides the upper yarn pulled out from the spool 6 to the auxiliary yarn tensioner 130. The thread hook 55 and the thread guide 56 are respectively located on the left and upper sides of the main thread tensioner 110 and guide the upper thread that has passed through the auxiliary thread tensioner 130 and the main thread tensioner 110 to the balance 51. As will be described later, the main thread tensioner 110 includes a thread take-up spring 115, and the thread take-up spring 115 is positioned on a path for supplying the upper thread from the main thread tensioner 110 to the thread hook 55, and is one of the upper thread supply paths. Parts. The thread guide 57 is provided at a position facing the thread guide 56 on the left side of the balance 51, and guides the upper thread that has passed through the balance 51 to the needle bar 11. The thread guides 58 and 59 are provided at the lower end portion of the needle bar 11 and guide the upper thread guided by the thread guide 57 to the sewing needle 7.

  As shown in FIG. 4, the main thread tensioner 110 includes a thread tension base 111, a thread tension shaft 112, a first thread tension tray 113, a second thread tension tray 114, a thread take-up spring 115, a dish presser 116, and a thread tension spring 117. The fixing member 118 and the drive rod 119 are provided. The thread tension base 111 is a cylindrical pedestal having a shaft hole in the front-rear direction, and a thread tension shaft 112 is rotatably fixed at the center. The thread tension base 111 is fixed to the sewing machine frame with screws (not shown). The thread tension shaft 112 is a cylindrical shaft extending in the front-rear direction. The end of the thread tension shaft 112 is inserted into the shaft hole of the thread tension base 111 and fixed with a screw (not shown). The thread tension shaft 112 has a shaft hole (not shown) through which the drive rod 119 can be inserted. The thread tension shaft 112 has a male screw on the outer peripheral surface on the front end side, and can be screwed into the fixing member 118. The thread tension shaft 112 has a slit 112A on the side surface from the front end side to the vicinity of the center. The slit 112A is formed along the axis of the thread tension shaft 112 and communicates with the shaft hole. The slit 112A can be inserted with a bridge portion (not shown) of the plate presser 116 described later. The thread tension shaft 112 is fixed by inserting a thread take-up spring 115 made of a coil spring on the outer periphery of the body portion. The coiled portion of the thread take-up spring 115 is accommodated in the thread tension table 111. The thread take-up spring 115 forms a hook-shaped thread guide part 115 </ b> A in which one end of the coil shape protrudes from the outer periphery of the thread tension base 111. The thread take-up spring 115 has a spring force in the clockwise direction when viewed from the front, and can swing in the vertical direction.

  The first thread tension tray 113 and the second thread tension tray 114 are dish-shaped metal plates each having a shaft hole at the center. The 1st thread tension tray 113 and the 2nd thread tension tray 114 are arrange | positioned in the form which mutually faces a board surface, and each outer periphery curves in the direction which leaves | separates mutually. The first thread tension plate 113 passes the shaft hole through the thread tension shaft 112 with the concave surface facing the thread tension table 111 and faces the thread take-up spring 115. The second thread tension tray 114 passes the shaft hole through the thread tension shaft 112 with the convex side facing the first thread tension tray 113. The first thread tension tray 113 and the second thread tension tray 114 are rotatable with respect to the thread tension shaft 112. The dish presser 116 is a disk-shaped member and has a shaft hole at the center. The shaft hole of the dish presser 116 has a pair of semicircular shapes, and has a belt-like bridging portion (not shown) between them. The dish presser 116 has an annular protrusion (not shown) that makes one round in the circumferential direction on the outer periphery on one plate surface side. The plate presser 116 is in contact with the second thread tension plate 114 by passing the shaft hole through the thread tension shaft 112 with the plate surface on the projection side facing the second thread tension plate 114. The bridging portion of the tray presser 116 is located in the slit 112A of the thread tension shaft 112.

  The thread tension spring 117 is a coil spring whose outer diameter increases from the front end side toward the rear end side. The thread tension spring 117 is passed through the thread tension shaft 112 on the front side of the plate presser 116, and the rear end portion is disposed in the recess of the projection of the plate presser 116. The thread tension spring 117 urges the second thread tension tray 114 and the first thread tension tray 113 toward the thread tension base 111 via the tray presser 116. The fixing member 118 is a nut-like member and is screwed into a male screw provided at the front end of the thread tension shaft 112. The fixing member 118 can be screwed to the thread tension shaft 112 at an arbitrary position in the front-rear direction, and positions the front end of the thread tension spring 117. The force with which the thread tension spring 117 presses the second thread tension tray 114 and the first thread tension tray 113 toward the thread tension base 111 changes in accordance with the position of the fixing member 118 with respect to the thread tension shaft 112.

  The drive rod 119 is a thin rod, and is inserted into the shaft hole of the thread tension shaft 112 from the rear end of the thread tension base 111. The front end of the drive rod 119 comes into contact with the bridge portion of the plate presser 116 in the shaft hole of the thread tension shaft 112. The rear end of the drive rod 119 protrudes rearward from the rear end of the thread tension base 111 and comes into contact with the front end of the release pin 120. As described above, the main thread tensioner 110 sandwiches the upper thread between the first thread tension tray 113 and the second thread tension tray 114 by the urging force of the thread tension spring 117 during sewing, and tensions the upper thread. Give.

  The release pin 120 is a round bar member that extends in the front-rear direction. Although not shown, the release pin 120 is held by a holding member provided on a sewing machine frame (not shown) so as to be movable in the front-rear direction. In the release pin 120, the end surface of the front end portion 121 is planar, and the rear end portion 122 is hemispherical. In the release pin 120, the front end 121 abuts on the drive rod 119, and the rear end 122 abuts on the first cam surface 167 of the first arm 160 of the yarn release link mechanism 150 described later.

  The main thread tensioner 110 holds a restriction mechanism 180 extending between the release pin 120 and the vicinity of the first thread tension plate 113 along the outer periphery of the thread tension base 111. As shown in FIGS. 4 and 7, the restriction mechanism 180 includes a hole 181, a base portion 182, a body portion 183, and a contact portion 184. The hole portion 181 opens to the base portion 182 and has a diameter through which the drive rod 119 can be inserted. The base part 182 includes a disk part 182A and a fan part 182B. The disk portion 182A is a substantially oval plate shape having a hole 181 at the center. The fan portion 182B has a plate shape that extends in a fan shape in the radial direction from one of the radially outer circumferences of the disk portion 182A. The base portion 182 is located behind the thread tension base 111 with the drive rod 119 inserted through the hole portion 181. The body part 183 is a part obtained by extending the outer edge of the fan part 182B forward in an arc shape. The body portion 183 has an inner diameter side substantially the same diameter as the outer periphery of the thread tension table 111, and is disposed along the outer periphery of the thread tension table 111. The body portion 183 has a tapered surface 183A on a part of the side surface on the front end side.

  The contact portion 184 is an end portion on the front end side of the body portion 183. The contact portion 184 faces a protruding portion 111A (see FIG. 4) provided on the front end side of the thread tension base 111. The restriction mechanism 180 can move in the front-rear direction with respect to the thread tension base 111. The contact portion 184 sandwiches the yarn guide portion 115A of the yarn take-up spring 115 between the protruding portion 111A and can regulate the swing of the yarn take-up spring 115. The tapered surface 183A of the body portion 183 prevents interference between the hook-shaped portion of the yarn guide portion 115A and the body portion 183 when the thread take-up spring 115 is sandwiched between the contact portion 184 and the protruding portion 111A.

  The secondary thread tensioner 130 includes a thread tension base 131, a thread tension shaft 132, a first thread tension tray 133, a second thread tension tray 134, a thread guide 135, a tray presser 136, a thread tension spring 137, a fixing member 138, and a drive rod. 139. The secondary thread tensioner 130 has substantially the same configuration as that of the main thread tensioner 110, and thus the description of the same configuration and operation as the main thread tensioner 110 is omitted. As described above, the secondary thread tensioner 130 sandwiches the upper thread between the first thread tension tray 133 and the second thread tension tray 134 by the urging force of the thread tension spring 137 during thread trimming, and against the upper thread. Apply tension. The yarn guide 135 is a bent plate member extending in the vertical direction, and is positioned behind the first yarn tension plate 133. The yarn guide 135 has its both ends in the vertical direction bent forward and has a yarn guide hole (not shown). The thread guide 135 passes the upper thread passed through the thread guide 43 through the thread guide hole on the upper end side. The thread guide 135 passes the upper thread passed through the thread guide hole on the upper end side between the first thread tension tray 133 and the second thread tension tray 134, and passes through the thread guide hole on the lower end side to the main thread tensioner 110. Guide you towards.

  The drive rod 139 of the secondary thread tensioner 130 contacts the front end of the switching pin 140. The switching pin 140 is a round bar-like member extending in the front-rear direction. The switching pin 140 is held in a state of being movable in the front-rear direction by a holding member (not shown) provided on the sewing machine frame (not shown). The switching pin 140 has a flat end surface at the front end portion 141 and a hemispherical shape at the rear end portion 142. Similar to the release pin 120, the switching pin 140 has a front end portion 141 that abuts against the drive rod 139 and a rear end portion 142 that abuts a second cam surface 177 of a second arm portion 170 of the thread release link mechanism 150 described later. .

  As shown in FIGS. 4 to 6, the thread release link mechanism 150 includes a first arm portion 160 and a second arm portion 170. The first arm portion 160 is an elongated plate that extends in the vertical direction and directs the plate surface in the front-rear direction. The first arm portion 160 includes an upper end portion 161 and a lower end portion 162 at both ends in the vertical direction. The first arm portion 160 has a cam base portion 163 that protrudes to the right at the lower end portion 162. The first arm portion 160 is bent stepwise in the thickness direction at the body portion 165 between the upper end portion 161 and the lower end portion 162, and the lower end portion 162 side is positioned forward of the upper end portion 161 side (see FIG. 4). The first arm portion 160 has a support hole 164 that fits in a support shaft 152 fixed to a sewing machine frame (not shown) at a lower end portion 162. The first arm portion 160 can rotate about the support shaft 152 as a fulcrum.

  The first arm portion 160 includes a first cam piece 166 at the upper right end portion of the cam base portion 163. The first cam piece 166 has a slope portion formed by bending forward from a connection portion with the cam base portion 163 and a plane portion extending substantially parallel to the surface of the cam base portion 163 from the upper end of the slope portion. A surface 167 is provided. The rear end portion 122 of the release pin 120 abuts on the first cam surface 167 of the first cam piece 166. When the first arm portion 160 rotates about the support shaft 152, the rear end portion 122 of the release pin 120 slides on the first cam surface 167.

  The first arm portion 160 includes a support pin 151 at the upper end portion 161. The support pin 151 rotatably supports the lower end portion 172 of the second arm portion 170 and allows relative rotation between the upper end portion 161 and the lower end portion 172. The support pin 151 protrudes toward the rear surface side of the first arm portion 160. The first arm portion 160 includes a hook portion 168 at the upper end portion 161. The hooking portion 168 hooks and holds a fastening portion 196 provided at one end of a wire 195 described later. The hanging portion 168 is provided below the support pin 151 of the upper end portion 161 and the right end portion is folded forward. The hanging portion 168 is located on the right side of the fastening portion 196 of the wire 195. When the wire 195 is pulled to the right side, the hanging portion 168 moves to the right side together with the upper end portion 161 via the fastening portion 196, and rotates the first arm portion 160 clockwise.

  The first arm portion 160 includes a return protrusion 169 extending downward from the lower end portion 162. The return protrusion 169 engages with one end of a spring (not shown). The other end of the spring is fixed to the sewing machine frame. The spring moves the lower end portion 162 of the first arm portion 160 to the left side via the return protrusion 169 and rotates the first arm portion 160 counterclockwise.

  The second arm portion 170 is an elongated plate body that extends in the vertical direction and faces the plate surface in the front-rear direction, like the first arm portion 160. The second arm portion 170 is shorter than the first arm portion 160. The second arm portion 170 includes an upper end portion 171 and a lower end portion 172 at both ends in the vertical direction. The second arm 170 has a cam base 173 that protrudes to the right at the upper end 171. The second arm 170 is bent stepwise in the thickness direction at the body 175 between the upper end 171 and the lower end 172. The lower end portion 172 side of the second arm portion 170 is located behind the upper end portion 171 side (see FIG. 4). The second arm portion 170 has a support hole 174 that fits into a support shaft 153 fixed to a sewing machine frame (not shown) at the upper end portion 171. The second arm portion 170 can rotate about the support shaft 153 as a fulcrum.

  The second arm portion 170 includes a second cam piece 176 that protrudes upward from the right end portion of the cam base portion 173. The second cam piece 176 has a slope portion formed by bending forward from the connection portion with the cam base portion 173 and a flat portion extending substantially parallel to the surface of the cam base portion 173 from the upper end of the slope portion. A surface 177 is provided. The rear end portion 142 of the switching pin 140 contacts the second cam surface 177 of the second cam piece 176. When the second arm portion 170 rotates about the support shaft 153, the rear end portion 142 of the switching pin 140 slides on the second cam surface 177.

  The second arm portion 170 opens a long hole 178 (see FIG. 6) in the lower end portion 172. The elongated hole 178 can be inserted with a support pin 151 provided on the upper end portion 161 of the first arm portion 160 and extends long in the vertical direction. The second arm portion 170 is arranged with the lower end portion 172 overlapped with the rear surface side of the upper end portion 161 of the first arm portion 160, and the support pin 151 is inserted into the elongated hole 178. The support pin 151 can move along the inner peripheral surface of the long hole 178, and the lower end 172 of the second arm 170 can be rotated relative to the upper end 161 of the first arm 160.

  As shown in FIG. 3, the thread tension mechanism 100 configured as described above is connected to a thread trimming solenoid 190 via a wire 195. As described above, the thread trimming solenoid 190 is a power source that operates the thread trimming mechanism 90, and is provided in the bed portion 2 (see FIG. 1) of the sewing machine 1. The plunger 191 of the thread trimmer solenoid 190 extends to the right from the thread trimmer solenoid 190. Plunger 191 is connected to one end side of solenoid lever 192 on the right side of thread trimming solenoid 190. The other end side of the solenoid lever 192 is pivotally supported by the bed 2 so as to be rotatable. When the thread trimming solenoid 190 is driven, the plunger 191 rotates the solenoid lever 192. The solenoid lever 192 includes a protrusion 193 and a fixing part 194. The protrusion 193 protrudes to the left at the center in the front-rear direction of the solenoid lever 192. The protrusion 193 transmits power to the thread trimmer cam lever shaft (not shown) by the rotation of the solenoid lever 192 to operate the thread trimmer cam (not shown) and drive the thread trimmer mechanism 90. The fixed portion 194 extends downward from the solenoid lever 192. The fixing portion 194 fixes the other end portion of the wire 195. The wire 195 is inserted through the tube 197 laid in the bed portion 2, the pedestal portion 3, and the arm portion 4, and the fastening portion 196 at one end reaches the hanging portion 168 of the first arm portion 160.

  Next, the operation of the thread tension mechanism 100 will be described. As described above, the thread tension mechanism 100 is connected to the thread trimming solenoid 190 via the wire 195. The plunger 191 of the thread trimmer solenoid 190 maintains a state of protruding rightward from the thread trimmer solenoid 190 main body during sewing. The solenoid lever 192 is located on the side where the fixing portion 194 is separated from the thread trimming solenoid 190. In the thread release link mechanism 150 of the thread tension mechanism 100, the upper end portion 161 of the first arm portion 160 rotates leftward with the support shaft 152 as a fulcrum. The lower end portion 172 of the second arm portion 170 rotates to the right with the support shaft 153 as a fulcrum via the support pin 151 in the elongated hole 178 (see FIG. 6). Therefore, the first arm portion 160 and the second arm portion 170 are arranged such that the upper end portions 161 and 171 and the lower end portions 162 and 172 are arranged in a straight line in the vertical direction (see FIG. 5).

  As shown in FIG. 5, the release pin 120 has a rear end portion 122 (see FIG. 4) located at a connection portion between the slope portion of the first cam surface 167 and the cam base portion 163. As shown in FIG. 4, the drive rod 119 of the main thread tensioner 110 is not subjected to the pressing force by the release pin 120 and does not press the dish presser 116. Therefore, the main thread tensioner 110 is in a state in which the upper thread is sandwiched by the urging force of the thread tension spring 117 between the first thread tension tray 113 and the second thread tension tray 114 and tension is applied to the upper thread. .

  On the other hand, as shown in FIG. 5, the switching pin 140 has the rear end portion 142 located in the vicinity of the connection portion between the inclined surface portion and the flat surface portion of the second cam surface 177. As shown in FIG. 4, the drive rod 139 of the secondary thread tensioner 130 receives a pressing force directed forward by the switching pin 140 and presses the plate presser 136. The plate presser 136 pushes the thread tension spring 137 forward against the biasing force, and the second thread tension tray 134 loosens the force of pressing the first thread tension tray 133. The secondary thread tensioner 130 is in a state where the state of applying tension to the upper thread is released. The state in which the tension is released is not limited to a state in which the tension applied to the upper thread is zero, but includes a state in which the tension is slightly applied. When the upper thread is slightly tensioned, the tension is sufficiently small so as not to affect the sewing. The tension in the state where the tension is released depends on the moving length of the drive rod 139 in the front-rear direction. That is, if the inclination angle of the inclined surface portion of the second cam surface 177 is changed, the moving length of the drive rod 139 changes, and the tension in a state where the tension is released can be changed. The tension when the tension is released is, for example, a state in which a compression spring is provided between the first thread tension tray 133 and the thread guide 135 and the first thread tension tray 133 presses the second thread tension tray 134 with a sufficiently small force. You may make. The same applies to the main thread tensioner 110.

  When sewing is completed, the sewing machine 1 inputs a thread trimming signal at the time of thread trimming. The thread trimming solenoid 190 is driven by a thread trimming signal and pulls the plunger 191 into the interior. The other end side of the solenoid lever 192 moves to the thread trimming solenoid 190 side, and pulls the wire 195 through the fixing portion 194. The driving force of the thread trimming solenoid 190 is transmitted to the thread releasing link mechanism 150 via the wire 195 and the fastening portion 196.

  As shown in FIGS. 8 and 9, when the thread trimming solenoid 190 pulls the wire 195, the fastening portion 196 of the wire 195 moves to the right. The hanging portion 168 around which the retaining portion 196 is hung is pulled rightward and moves the upper end portion 161 to the right. When the upper end 161 moves to the right, the first arm 160 rotates clockwise around the support shaft 152 as a fulcrum. The support pin 151 of the upper end portion 161 moves on the inner peripheral surface of the long hole 178 of the lower end portion 172 of the second arm portion 170. The lower arm 172 moves to the right, and the second arm 170 rotates counterclockwise with the support shaft 153 as a fulcrum.

  As the first arm portion 160 rotates, the first cam piece 166 moves to the lower left with the support shaft 152 as a fulcrum. As the first cam piece 166 moves, the rear end 122 of the release pin 120 enters the inclined surface portion from the connection portion with the cam base portion 163 and slides on the first cam surface 167 toward the flat surface portion. The first cam surface 167 presses the release pin 120 forward. The drive rod 119 of the main thread tensioner 110 is pressed by the release pin 120 and presses the plate presser 116. The plate presser 116 presses the thread tension spring 117 forward against the urging force, and loosens the force with which the second thread tension tray 114 presses the first thread tension tray 113. The main yarn tensioner 110 is in a state where the state of applying tension to the upper yarn is released.

  The release pin 120 presses the base portion 182 of the restriction mechanism 180 when the drive rod 119 is pressed. The restriction mechanism 180 moves forward, and the contact portion 184 sandwiches the yarn guide portion 115A of the yarn take-up spring 115 between the protruding portion 111A. Therefore, the restriction mechanism 180 can reliably restrict the rotation of the yarn guide portion 115A.

  On the other hand, as the second arm portion 170 rotates, the second cam piece 176 moves to the upper left with the support shaft 153 as a fulcrum. Along with the movement of the second cam piece 176, the switching pin 140 slides on the second cam surface 177 from the vicinity of the connection position between the inclined surface portion and the flat surface portion to the connection portion between the rear end portion 142 and the cam base portion 173. The drive rod 139 of the secondary thread tensioner 130 loosens the pressing force by the switching pin 140 and loosens the pressing force to the plate presser 136. The plate presser 136 is urged backward by the thread tension spring 137. Therefore, the secondary thread tensioner 130 is in a state in which the upper thread is sandwiched by the urging force of the thread tension spring 137 between the first thread tension tray 133 and the second thread tension tray 134 and tension is applied to the upper thread. .

  At the time of thread trimming, a wire 195 that transmits the power of the thread trimming solenoid 190 rotates the first arm portion 160 and the second arm portion 170 simultaneously. While the release pin 120 slides on the first cam surface 167, the switching pin 140 slides on the second cam surface 177. That is, an intermediate state in the process from the state in which the main thread tensioner 110 applies tension to the upper thread to the state in which the upper thread tensioner is released and the state in which the tension applied to the upper thread by the auxiliary thread tensioner 130 is released to the state in which the tension is applied. Intermediate states in the process occur simultaneously. The thread tension mechanism 100 causes a time lag from when the main thread tensioner 110 starts releasing the tension to the upper thread until the sub thread tensioner 130 applies the tension to the upper thread. Therefore, the thread tension mechanism 100 has a time at which the holding of the upper thread by the main thread tensioner 110 and the holding of the upper thread by the auxiliary thread tensioner 130 can be canceled at the same time. The tension can be zero or close to zero.

  As shown in FIG. 10, the thread trimming solenoid 190 is driven by the input of the thread trimming signal when the rotational position of the main shaft 41 is at 230 °. The yarn is cut by the movable blade and the fixed blade when the main shaft 41 exceeds 360 ° and further reaches 35 °. When the tension is released from the upper thread by the main thread tensioner 110 and the tension is applied to the upper thread by the auxiliary thread tensioner 130 when the thread tension mechanism 100 performs thread trimming, the main shaft 41 starts from 230 °. It is good to carry out at the time located between 360 degrees. The timing adjustment described above is performed by adjusting the size and the inclination angle of the inclined portions of the first cam surface 167 and the second cam surface 177, and the support shafts 152 and 153 to the first cam piece 166 and the second cam piece 176, respectively. This is possible by changing the distance or the like.

  As described above, in the sewing machine 1 of the present embodiment, at the time of sewing, the main thread tensioner 110 applies tension to the upper thread, and the auxiliary thread tensioner 130 releases tension applied to the upper thread. The upper thread can obtain a proper tension from the main thread tensioner 110 and form a seam together with the lower thread. During thread trimming, the thread release link mechanism 150 drives the release pin 120 and the switching pin 140 in synchronization. The main thread tensioner 110 releases the tension applied to the upper thread, and the sub thread tensioner 130 applies tension to the upper thread. Thus, the sewing machine 1 can cut the upper thread with an appropriate tension from the auxiliary thread tensioner 130. The yarn release link mechanism 150 mechanically drives the release pin 120 and the switching pin 140. Therefore, the release pin 120 and the switching pin 140 can operate reliably without being out of synchronization.

  At the time of thread trimming, the sewing machine 1 can drive the thread trimming mechanism 90 via the thread trimming solenoid 190 and operate the release pin 120 and the switching pin 140 by the thread release link mechanism 150 in conjunction with each other.

  The thread release link mechanism 150 is driven by power transmitted from one thread trimming solenoid 190 via a wire 195. Therefore, the sewing machine 1 can be manufactured at low cost. The sewing machine 1 drives the thread release link mechanism 150 with a single thread trimming solenoid 190, so that there is no deviation in the synchronization timing, and the tension at the time of sewing and the tension at the time of cutting are accurately applied to the upper thread. Can do. In the thread release link mechanism 150, the first arm portion 160 and the second arm portion 170 are supported by the support pin 151 and rotate in conjunction with each other, so that the transmission of power to the release pin 120 and the switching pin 140 is reliably synchronized. Can be done. The sewing machine 1 synchronizes the sliding of the release pin 120 with the first cam surface 167 and the sliding of the switching pin 140 with the second cam surface 177. Therefore, the sewing machine 1 can temporarily and simultaneously cause the state in which the application of the tension by the main thread tensioner 110 is released and the state in which the application of the tension by the auxiliary thread tensioner 130 is released. The sewing machine 1 can apply the tension at the time of thread trimming after reducing the tension at the time of sewing to the upper thread at the time of thread trimming. Therefore, the sewing machine 1 can cut the upper thread in an excessively stretched state and suppress variations in the remaining thread length of the upper thread to the sewing needle 7.

  The yarn release link mechanism 150 restricts the swinging of the yarn take-up spring 155 by operating the restriction mechanism 180 with the release pin 120 while releasing the tension applied to the upper yarn by the main yarn tensioner 110. The sewing machine 1 can prevent the yarn take-up spring 155 from rotating when the upper thread is cut, and the amount of yarn remaining in the upper thread from being cut off varies.

  In the present embodiment, the main thread tensioner 110 corresponds to a “first thread tensioner”. The secondary thread tensioner 130 corresponds to a “second thread tensioner”. The release pin 120 corresponds to a “release mechanism”. The switching pin 140 corresponds to a “switching mechanism”. The yarn release link mechanism 150 corresponds to a “drive mechanism”. The thread trimming solenoid 190 corresponds to a “power source”. The wire 195 corresponds to a “transmission member”. The support pin 151 corresponds to a “support portion”. The hanging portion 168 corresponds to the “connecting portion”.

  The present invention can be variously modified in addition to the above-described embodiment. Although the wire 195 is used for power transmission from the thread trimming solenoid 190 to the thread tension mechanism 100, transmission may be performed using other mechanical configurations such as a gear and a lever. A solenoid interlocking with the thread trimming solenoid 190 may be provided in the thread tension mechanism 100 to drive the thread tension mechanism 100. The rotation directions of the first arm portion 160 and the second arm portion 170 are examples, and may be rotated in a direction different from the embodiment. In this case, the plane portions and the slope portions of the first cam surface 167 and the second cam surface 177 may be changed in accordance with the rotational directions of the first arm portion 160 and the second arm portion 170. The first arm portion 160 and the second arm portion 170 may be integrally formed. In this case, the integrally configured arm may transmit the drive of the thread trimming solenoid 190 to both the release pin 120 and the switching pin 140.

  The first and second cam surfaces 167 and 177 are displaced from each other in the plane portion and the slope portion, and the application of tension by the main thread tensioner 110 at the time of thread trimming is started. Alternatively, it may be performed before. For example, the formation position of the second cam piece 176 may be changed so that the rear end portion 142 of the switching pin 140 is positioned on the flat portion of the second cam surface 177 during sewing. For example, the cam base 173 may be formed so as to be shifted to a position closer to the lower end 172 of the second arm 170 than the position of the embodiment. The sewing machine creates a state where the tension from both the main thread tension device 110 and the sub thread tension device 130 is not applied to the upper thread, or the tension is reduced. Accordingly, the sewing machine can apply the tension at the time of thread trimming after releasing the tension remaining on the thread after sewing. When the thread is trimmed while the tension at the time of sewing remains, there is a possibility that the thread jumps after thread trimming and the thread is pulled out from the sewing needle. By releasing the tension at the time of sewing as described above, the sewing machine can prevent the occurrence of thread dropout.

DESCRIPTION OF SYMBOLS 1 Sewing machine 7 Sewing needle 41 Main shaft 51 Balance 90 Thread trimming mechanism 100 Thread tension mechanism 110 Main thread tensioner 115 Thread take-up spring 120 Release pin 130 Sub thread tensioner 140 Switching pin 150 Thread release link mechanism 151 Support pin 160 First arm part 161 Upper end Portion 162 lower end portion 167 first cam surface 168 hanging portion 170 second arm portion 171 upper end portion 172 lower end portion 177 second cam surface 180 regulating mechanism 190 thread trimming solenoid 195 wire

Claims (5)

A sewing needle that passes through the upper thread and moves up and down by the rotation of the main shaft;
A scale that moves up and down in conjunction with the vertical movement of the sewing needle;
In a sewing machine that is located upstream of the balance supply path of the upper thread and has a thread tension mechanism that can apply tension to the upper thread,
The thread tension mechanism is
The first thread tensioner,
A second thread tensioner located on the upstream side of the upper thread supply path from the first thread tensioner;
A release mechanism for releasing the tension applied to the upper thread by the first thread tensioner;
A switching mechanism for switching from a state where the tension applied to the upper thread by the second thread tensioner is released to a state where it can be applied;
A sewing machine comprising: a drive mechanism that drives the release mechanism and the switching mechanism in synchronization. A thread trimming mechanism for cutting the upper thread;
A power source for applying power for driving the thread trimming mechanism;
A transmission member for transmitting power to the drive mechanism;
The sewing machine according to claim 1, wherein the transmission member is connected to the power source. The drive mechanism is
A first arm having a first cam surface on which one end is pivotally supported by the sewing machine frame at a position closer to the release mechanism than the switching mechanism, and the release mechanism slides on the one end;
A second arm portion having one end portion rotatably supported by the sewing machine frame at a position closer to the switching mechanism than the release mechanism, and having a second cam surface on which the switching mechanism slides at the one end portion; ,
A support part that rotatably supports the other end part of the first arm part and the other end part of the second arm part;
A connection portion provided on the other end portion side of the first arm portion at a position closer to the one end portion than the support portion and connected to the transmission member;
The power source rotates the first arm portion and the second arm portion by moving the position of the support portion via the transmission member, and the first cam surface and the second cam surface, respectively. The sewing machine according to claim 2, wherein the release mechanism and the switching mechanism that respectively slide are driven.   When the power source is driven, the first cam surface and the second cam surface slide the release mechanism on the first cam surface rather than slide the switching mechanism on the second cam surface. The sewing machine according to claim 3, further comprising a cam surface as a tip. A thread take-up spring that is provided in the first thread tensioner and swings up and down with the movement of the upper thread by the vertical movement of the balance;
The sewing machine according to any one of claims 1 to 4, further comprising: a restriction mechanism that transmits power by the release mechanism and restricts swinging of the thread take-up spring up and down.

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