Patent Publication Number: US-9845557-B2

Title: Sewing machine

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims the benefit of priority to Japanese Patent Application No. 2014-159790 filed on Aug. 5, 2014, the contents of which are hereby incorporated by reference in their entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to a sewing machine capable of performing chain stitching. 
     DESCRIPTION OF THE RELATED ART 
     Sewing machines capable of performing chain stitching are conventionally known. The applicants of the present invention have suggested sewing machines which perform chain stitching using only needle threads in sewing machines which perform lock stitching using needle threads and bobbin threads (see Patent Literature 1, Patent Literature 2 and Patent Literature 3). Such chain stitching differs from cases of lock switching in that one surface is configured similarly to lock switching using a single thread while the other surface on the opposite side is sewn in a shape of a chain. Since such sewing machines capable of performing chain stitching can correspond to use such as basting and seal stitches, they have been suggested as sewing machines which enlarges the available range of sewing machines. 
     However, all of sewing machines according to the above-mentioned suggestions are sewing machines comprising perpendicular hooks, and the inventions could not be applied to sewing machines comprising horizontal hooks. 
     Sewing machines capable of performing chain stitching using only needle threads in sewing machines comprising horizontal hooks are disclosed in Patent Literature 4 and Patent Literature 5. 
     PRIOR ART LITERATURE 
     Patent Literature 
     [Patent Literature 1] Japanese Patent Publication No. S45-33108 
     [Patent Literature 2] Japanese Patent Publication No. S49-18739 
     [Patent Literature 3] Japanese Patent Publication No. S56-20032 
     [Patent Literature 4] Japanese Patent Publication No. S56-47787 
     [Patent Literature 5] Japanese Patent Publication No. H03-66911 
     SUMMARY OF THE INVENTION 
     However, according to the techniques of Patent Literature 4 and Patent Literature 5, special structures were required on throat plate sides since thread holding of a single thread was difficult due to their structures, and since preparing operations where complicated since exclusive thread holders and throat plates were required and other factors, the sewing machines could not be used easily. 
     One or more embodiments of the present invention provide a sewing machine with a simple configuration in which chain stitching can be easily performed even when the sewing machine comprises a horizontal hook. 
     Embodiment (1): One or more embodiments of the present invention provide a sewing machine comprising a horizontal hook that rotates twice around a vertical center of rotation with respect to a reciprocating direction of a needle when the needle performs a single reciprocating movement in the up and down direction, wherein the horizontal hook comprises an outer hook including a hook point that captures a thread loop of a needle thread and an accommodating portion that is formed to open upwardly, a chain looper that is held within the accommodating portion of the outer hook to be attachable/detachable to and from the outer hook and to move integrally with the outer hook, that includes a spiral-shaped columnar portion to which the thread loop captured by the hook point is wound, and that rotates together with the pulling the thread up and the rotation of the outer hook to guide the thread loop induced in spiral shape upward, and an inner hook for chain stitching that is supported by the outer hook, that forms a thread space upward of the chain looper and that restricts upward movement of the thread loop drawn into the interior of the outer hook. 
     Embodiment (2): One or more embodiments of the present invention provide the sewing machine of Embodiment (1), wherein the chain looper is held in the accommodating portion of the outer hook at a position concentric with the center of rotation of the outer hook. 
     Embodiment (3): One or more embodiments of the present invention provide the sewing machine of Embodiment (1), wherein the inner hook for chain stitching further guides a thread loop drawn into the interior of the outer hook out of the thread loop that has been captured by the hook point to the chain looper. 
     Embodiment (4): One or more embodiments of the present invention provide the sewing machine of Embodiment (1), wherein the accommodating portion of the outer hook is formed such that an inner hook for lock stitching can be mounted instead of the chain looper and the inner hook for chain stitching. 
     Embodiment (5): One or more embodiments of the present invention provide the sewing machine of Embodiment (1), wherein a thread loop guiding portion for guiding a thread loop is formed on a lower surface of the inner hook for chain stitching. 
     Embodiment (6): One or more embodiments of the present invention provide the sewing machine of Embodiment (5), wherein the thread loop guiding portion is formed to become narrower towards a downward tip thereof. 
     Embodiment (7): One or more embodiments of the present invention provide the sewing machine of Embodiment (5), wherein the tip of the thread loop guiding portion is disposed proximate of a base of the spiral-shaped columnar portion at which the spiral-shaped columnar portion receives the thread loop. 
     According to one or more embodiments of the present invention, it is possible to realize a sewing machine with a simple configuration in which chain stitching can be easily performed even when the sewing machine comprises a horizontal hook. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  A view showing an embodiment of the sewing machine according to the present invention. 
         FIG. 2  An exploded perspective view of a horizontal hook  20 . 
         FIG. 3  A view in which the horizontal hook  20  is seen from above. 
         FIG. 4  A sectional view at a position of arrow X-X shown in  FIG. 3 . 
         FIG. 5  A sectional view at a position of arrow Y-Y shown in  FIG. 3 . 
         FIG. 6  A perspective view in which an inner hook for chain stitching  24  is seen from below. 
         FIG. 7  A sectional view showing a state in which an inner hook for lock stitching  26  is mounted to an accommodating portion  21   b  of an outer hook  21 . 
         FIG. 8A  A view showing a process of performing chain stitching. 
         FIG. 8B  A view showing a process of performing chain stitching. 
         FIG. 8C  A view showing a process of performing chain stitching. 
         FIG. 8D  A view showing a process of performing chain stitching. 
         FIG. 8E  A view showing a process of performing chain stitching. 
         FIG. 8F  A view showing a process of performing chain stitching. 
         FIG. 8G  A view showing a process of performing chain stitching. 
         FIG. 8H  A view showing a process of performing chain stitching. 
         FIG. 8I  A view showing a process of performing chain stitching. 
         FIG. 8J  A view showing a process of performing chain stitching. 
         FIG. 8K  A view showing a process of performing chain stitching. 
         FIG. 8L  A view showing a process of performing chain stitching. 
         FIG. 8M  A view showing a process of performing chain stitching. 
         FIG. 8N  A view showing a process of performing chain stitching. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A best mode for embodying the present invention will now be explained while referring to the drawings and others. 
     &lt;Embodiment&gt; 
       FIG. 1  is a view showing an embodiment of the sewing machine according to the present invention. 
     In this respect, each of the drawings including  FIG. 1  indicated hereinafter are schematically illustrated drawings, and sizes and shapes of respective portions are shown in suitably exaggerated form for ease of understanding. 
     Further, while explanations are made upon indicating specific numerical values, shapes and materials in the following explanations, they may be suitably changed. 
     The sewing machine  1  according to the present embodiment comprises a needle  10  and a horizontal hook  20 . 
     The needle  10  performs reciprocating movements in the up and down direction (vertical direction) when performing sewing when the sewing machine  1  is correctly set up on a horizontal set up surface. 
     The horizontal hook  20  is at a position that the needle  10  reaches when it has moved downward in its movable range, and it is set up in an interior of the sewing machine  1  such that it rotates twice around a vertical center of rotation with respect to the reciprocating direction of the needle  10  when the needle  10  performs a single reciprocating movement in the up and down direction. 
       FIG. 2  is an exploded perspective view of a horizontal hook  20 . 
       FIG. 3  is a view in which the horizontal hook  20  is seen from above. 
       FIG. 4  is a sectional view at a position of arrow X-X shown in  FIG. 3 . 
       FIG. 5  is a sectional view at a position of arrow Y-Y shown in  FIG. 3 . 
     The horizontal hook  20  includes an outer hook  21 , a magnet  22 , a chain looper  23  and an inner hook for chain stitching  24 . 
     The outer hook  21  comprises a hook point  21   a , an accommodating portion  21   b  and a gear portion  21   c . In this respect, while the outer hook  21  according to the present embodiment is configured of a plurality of parts for ease of manufacture, these parts might suitably be integrated. 
     The hook point  21   a  is provided along an outer peripheral surface of the outer hook  21  and I formed into a shape having a pointed tip for capturing a needle thread loop (thread loop) of the needle thread  30  that passes through the needle  10  (see  FIG. 8A  and others). 
     The accommodating portion  21   b  is formed to open upwardly to accommodate the chain looper  23  and the inner hook for chain stitching  24 . 
     The gear portion  21   c  is mounted integrally with the outer hook  21  to rotate around a shaft  25  as a center of rotation that projects in a substantially columnar shape downward of the accommodating portion  21   b . The gear portion  21   c  is in mesh with a driving gear that is provided at a driving shaft (not shown). The outer hook  21  rotates in sync with up and down movements of the needle  10  when the gear portion  21   c  receives driving force from the driving gear. 
     The magnet  22  is fixed to a lower bottom portion within the accommodating portion  21   b  by using an adhesive or the like. 
     The chain looper  23  includes a disk portion  23   a  and a spiral-shaped columnar portion  23   b , and is held within the accommodating portion  21   b  of the outer hook  21  and at a position concentric with the center of rotation of the outer hook  21  to be attachable/detachable to and from the outer hook  21  and to move integrally with the outer hook  21 . 
     The disk portion  23   a  is formed at a lower end side of the chain looper  23  to expand in a substantially disk-like shape. The disk portion  23   a  mates with a shape of the lower bottom portion of the accommodating portion  21   b  to integrally attach the chain looper  23  with respect to the outer hook  21 . 
     The spiral-shaped columnar portion  23   b  projects upwardly from the disk portion  23   a  in a substantially columnar shape, and a spiral shape is formed on an outer peripheral surface thereof. A needle thread loop (thread loop) captured by the hook point  21   a  is wound to the spiral-shaped columnar portion  23   b . The chain looper  23  rotates together with pulling the thread up and the rotation of the outer hook  21 , and the needle thread loop induced by the spiral shape of the spiral-shaped columnar portion  23   b  is guided upward together with the rotation of the outer hook  21 . 
     The inner hook for chain stitching  24  is located further upward of the chain looper  23 , and is supported by a wall-like portion that forms an outer periphery of the outer hook  21 . 
     The inner hook for chain stitching  24  is formed to have a substantially disk-like shape to substantially cover an aperture of the accommodating portion  21   b , and includes a first thread guiding portion  24   a , a first cam surface  24   b , a second thread guiding portion  24   c , a protruding portion  24   d , a second cam surface  24   e  and a thread space  24   f.    
     The first thread guiding portion  24   a  has a small protruding shape in form of a hook projecting towards the thread space  24   f  side. The first thread guiding portion  24   a  assists reliable guidance of a thread located inside of the outer hook  21  out of the needle thread loop captured by the hook point  21   a  to downside of the hook point  21   a.    
       FIG. 6  is a perspective view in which the inner hook for chain stitching  24  is seen from below. 
     The first cam surface  24   b  projects downward from the inner hook for chain stitching  24  and has an annular shape of which a portion corresponding to the thread space  24   f  is cut off. The first cam surface  24   b  functions as a thread loop guiding portion which guides the needle thread loop (thread loop) guided downside by the first thread guiding portion  24   a  to form a needle thread loop (thread loop) that is larger than a diameter of the chain looper  23  and further guides it to a predetermined position of the spiral-shaped columnar portion  23   b  of the chain looper  23 . The first can surface  24   b  is formed to become narrower towards a downward tip thereof. Further, the tip of the first cam surface  24   b  is disposed proximate of a starting position of the spiral shape at which the spiral-shaped columnar portion  23   b  receives the thread loop, namely, proximate of a base  23   c  of the spiral-shaped columnar portion  23   b . Since the first cam surface  24   b  that functions as a thread loop guiding portion is disposed in this manner, it is possible to reliably wind the needle thread loop (thread loop) to the spiral-shaped columnar portion  23   b.    
     The second thread guiding portion  24   c  is a surface that is warped in a substantially arc-like shape that projects upward of the inner hook for chain stitching  24 . The second thread guiding portion  24   c  guides the thread upside of the needle thread loop captured by the hook point  21   a  to reliably pass an upper portion of the chain looper  23 . 
     The protruding portion  24   d  is formed to slightly project to the outer peripheral side beyond the accommodating portion  21   b . The protruding portion  24   d  assists stabilization of a phase at which the hook point  21   a  releases the needle thread loop to be of constant phase. 
     The second cam surface  24   e  is a cam surface formed close to an outer periphery upward of the inner hook for chain stitching  24  and is disposed at a position on a substantially opposite side of the second thread guiding portion  24   c . The second cam surface  24   e  guides the needle thread loop that is released by the hook point  21   a  to a predetermined position of the spiral-shaped columnar portion  23   b  of the chain looper  23 . 
     The thread space  24   f  is formed to have a shape in which an outer peripheral portion of the inner hook for chain stitching  24  is partially removed. The thread space  24   f  is provided such that the thread can fall off to upward of the chain looper  23 . 
     With the above configuration, the inner hook for chain stitching  24  restricts upward movement of the needle thread loop that has been drawn into the interior of the outer hook  21 . 
     Here, the inner hook for chain stitching  24  is formed, for instance, by means of a ferromagnetic body such as steel or the like, and its position is maintained by the magnetic force of the magnet  22  so that it does not come off the outer hook  21 . 
     The accommodating portion  21   b  of the outer hook  21   b  is formed such that an inner hook for lock stitching  26  can be mounted instead of the chain looper  23  and the inner hook for chain stitching  24 . 
       FIG. 7  is a sectional view showing a state in which the inner hook for lock stitching  26  is mounted to the accommodating portion  21   b  of the outer hook  21 . 
     It is possible to attach a bobbin  27  reeled with the bottom thread to the inner hook for lock stitching  26 , and by assuming this state, the sewing machine  1  according to the present embodiment can perform usual lock stitching. 
     Next, operations when performing chain stitching using the sewing machine  1  according to the present embodiment will be explained. 
     First, preparations for chain stitching will be explained. 
     When the inner hook for lock stitching  26  is disposed in the outer hook  21 , the inner hook for lock stitching  26  is taken out from the outer hook  21 . 
     Next, the chain looper  23  is inserted into the accommodating portion  21   b  within the outer hook  21 , and the chain looper  23  is integrally attached to the outer hook  21 . 
     Then, the inner hook for chain stitching  24  is mounted onto an upper portion (rib portion) on an outer periphery of the outer hook  21  on an upper portion of the chain looper  23  to fix a throat plate (not shown) to the main body of the sewing machine. 
     Further, when the needle  10  is not threaded yet, the needle  10  is threaded. 
     In this manner, preparations for chain stitching are completed. 
     Next, chain stitching operations will be explained. 
       FIG. 8A  to  FIG. 8N  are views showing processes of performing chain stitching. 
     First, a needle thread loop generated below the throat plate through up and down movements of the needle  10  is captured by the outer hook  21  to draw it to downward of the inner hook for chain stitching  24 . 
     More specifically, the hook point  21   a  of the outer hook  21  captures the needle thread by means of the descended needle  10  ( FIG. 8A ). This process is identical to that for performing lock stitching. A thread positioned inside of the horizontal hook  20  out of the captured needle thread loop is sorted to downside of the hook point  21   a  while a thread positioned outside of the horizontal hook  20  is sorted to upside of the hook point  21   a  and is drawn by the hook point  21   a  ( FIG. 8B ,  FIG. 8C ). 
     Next, the needle thread loop is wound to the spiral-shaped columnar portion  23   b  of the chain loop  23  for holding the needle thread loop. Namely, a thread upside of the needle thread loop that has been drawn by the hook point  21   a  passes the upside of the chain looper  23  while a downside thread is guided by the first cam surface  24   b  of the inner hook for chain stitching  24  and is caught at a downward portion (proximate of the base  23   c ) of the spiral-shaped columnar portion  23   b  of the chain looper  23  ( FIG. 8C ,  FIG. 8D ). 
     Thereafter, when the hook point  21   a  of the outer hook  21  rotates up to a certain phase, the needle thread loop that had been hooked at the hook point  21   a  comes off the hook point  21   a  since the needle thread is pulled down by a take-up lever, and the needle thread loop is wound to a downward portion (proximate of the base  23   c ) of the spiral-shaped columnar portion  23   b  of the chain looper  23  ( FIG. 8D ,  FIG. 8E ). 
     The needle thread loop wound to the spiral-shaped columnar portion  23   b  of the chain looper  23  follows the spiral-shaped columnar portion  23   b  accompanying the rotation of the outer hook  21 , namely, the rotation of the chain looper  23  and moves upward of the spiral-shaped columnar portion  23   b  ( FIG. 8F ,  FIG. 8G ). 
     Next, the next descending needle  10  is made to progress into a loop constituted of the held needle thread loop and a cloth fed stitch. More specifically, the repeatedly descended needle  10  passes through the previous stitch and the needle thread loop formed by being caught at the chain looper  23 , and the hook point  21   a  of the outer hook  21  captures the needle thread of the descended needle  10 . Prior or after the capture, the spiral-shaped columnar portion  23   b  of the chain looper  23  releases the needle thread loop that had been wound thereto ( FIG. 8H ,  FIG. 8I , and  FIG. 8J ). 
     Then, the released needle thread loop is tightened by the action of the hook point  21   a  of the outer hook  21  dragging out a needle thread loop of the next stitch and by tightening with the take-up lever which is started at a slightly later phase so as to complete a chain stitch (chain stitch). 
     More specifically, a needle thread loop that is generated by an ascent of the needle  10  is captured and drawn by the outer hook  21  ( FIG. 8K ). 
     At the time of pulling the thread up by means of the take-up lever after capturing of the needle thread, the needle thread loop is guided by the spiral-shaped columnar portion  23   b  of the chain looper  23  to be induced upward ( FIG. 8L ). 
     The needle thread loop that has moved upward of the chain looper  23  is pulled upward through a clearance between the chain looper and the inner hook for chain stitching  24  to form a seam ( FIG. 8M ). 
     When the needle topmost point has been reached in the state of  FIG. 8M , the process returns to the state of  FIG. 8E  after assuming the state shown in  FIG. 8N , and by repeating sewing movements, the sewing machine  1  continues chain stitching. 
     As explained so far, according to the present embodiment, since the chain looper  23  and the inner hook for chain stitching  24  are provided inside the outer hook  21  in the sewing machine  1 , it is possible to realize chain stitching with a simple structure even if the sewing machine is comprised with a horizontal hook. 
     Further, it is possible to easily switch between lock stitching and chain stitching in the sewing machine  1  by merely exchanging small parts to easily perform chain stitching, and the application range of the sewing machine  1  comprised with a horizontal hook is remarkably improved. 
     Moreover, since the inner hook for chain stitching  24  is disposed on the upper portion of the chain looper  23  in the sewing machine  1 , unmanaged or irregular movements of the needle thread loop captured by the outer hook  21  can be restricted so that chain stitch seams can be reliably formed. 
     &lt;Modified Embodiment&gt; 
     The present invention is not limited to the above-described embodiment but may be variously modified and changed which are also included in the scope of the present invention. 
     For instance, the present embodiment has been explained based on a configuration in which the magnet  22  is fixed to the outer hook  21 . The present invention is not limited to this, and it is also possible to provide the magnet at the chain looper  23  or to provide the magnet on the inner hook for chain stitching  24  side. 
     Further, the present embodiment has been explained based on an example in which the position of the inner hook for chain stitching  24  is held using magnetic force of the magnet  22 . The present invention is not limited to this, and it is also possible to hold the inner hook for chain stitching without using magnetic force. 
     In this respect, while the embodiment and the modified embodiment can be used upon suitably combining them, detailed explanations will be omitted. The present invention is not to be limited by the above explained respective embodiments. 
     EXPLANATION OF THE REFERENCE NUMBERS 
     
         
           1  sewing machine 
           10  needle 
           20  horizontal hook 
           21  outer hook 
           21   a  hook point 
           21   b  accommodating portion 
           21   c  gear portion 
           22  magnet 
           23  chain looper 
           23   a  disk portion 
           23   b  spiral-shaped columnar portion 
           23   c  base of spiral-shaped columnar portion  23   b    
           24  inner hook for chain stitching 
           24   a  first thread guiding portion 
           24   b  first cam surface 
           24   c  second thread guiding portion 
           24   d  protruding portion 
           24   e  second cam portion 
           24   f  thread space 
           25  shaft 
           26  inner hook for lock stitching 
           27  bobbin 
           30  needle thread