Patent Publication Number: US-7913634-B2

Title: Sewing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. 2007-227821 filed on Sep. 3, 2007, the entire content of which is incorporated herein by reference. 
     FIELD OF INVENTION 
     The present invention relates to a sewing machine which is operable to form covering stitches. 
     DESCRIPTION OF RELATED ART 
     Related art sewing machines have three needles, through which needle threads are inserted respectively and which are arranged in a direction intersecting a cloth feeding direction, and a spreader with which a covering thread is controlled. More specifically, the spreader carries out, synchronously with a vertical motion of the three needles, a circular motion above a workpiece from a side of the needles toward a front of the needles to interlace the covering thread with the three needle threads. Synchronously with the interlacing operation of the spreader, a looper is rotated to interlace a looper thread with the needle threads below a throat plate on which the workpiece is placed, whereby a covering stitch is formed on the workpiece (see, e.g., JP 3693323 B2). 
     In a related art example, the spreader is attached to a top covering shaft, which is attached to a jaw portion of a sewing machine body, with a screw. In another related art example, the spreader is fitted into an inserting hole of a plastic lever, and an elastic deformation of a click portion of the lever is utilized to hold and to remove the spreader. 
     However, in a case in which the spreader is attached to the top covering shaft with the screw, it is necessary to fasten or to loosen the screw with a driver or a wrench when attaching or detaching the spreader, which is a time-consuming work for a user. In a case in which the spreader is attached to the lever by utilizing the elasticity of the plastic lever, on the other hand, there has been a problem that the elasticity of the lever deteriorates while being used, resulting in an unfirm holding of the spreader. 
     SUMMARY OF INVENTION 
     It is an object of the present invention to provide a sewing machine in which a spreader can be easily attached or detached. 
     According to an aspect of the present invention, a sewing machine is provided. The sewing machine includes a top covering shaft mechanism, a spreader mechanism detachably attached to the top covering shaft mechanism from below and operable to catch a covering thread and to interlace the covering thread with a needle thread inserted into a needle to form covering stitches, and an operating member having a hook portion and rotatably attached to either one of the top covering shaft mechanism and the spreader mechanism. The other of the top covering shaft mechanism and the spreader mechanism has a protrusion with which the hook portion is engageable. The operating member is rotatable between a position at which the hook portion engages with the protrusion to lock the spreader mechanism with respect to the top covering shaft mechanism and another position at which the spreader mechanism is detachable from the top covering shaft mechanism. 
     Other aspects and advantages of the invention will be apparent from the following description, the drawings and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a configuration around a jaw portion of a sewing machine according to an exemplary embodiment of the present invention; 
         FIG. 2  is a perspective view of a top covering shaft mechanism and a spreader mechanism of the sewing machine; 
         FIG. 3  is a perspective view of the top covering shaft mechanism; 
         FIG. 4  is a vertical sectional view taken along the line IV-IV of  FIG. 2 ; 
         FIG. 5  is a sectional view taken along the line V-V of  FIG. 2 ; 
         FIG. 6  is a perspective view illustrating a state in which the spreader mechanism is attached to the top covering shaft mechanism; and 
         FIG. 7  is a perspective view illustrating a state in which the spreader mechanism is detachable from the top covering shaft mechanism. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an exemplary embodiment of the invention will be explained with reference to the drawings. The following exemplary embodiment does not limit the scope of the invention. 
     As shown in  FIG. 1 , a sewing machine  100  includes a top covering shaft mechanism  2  disposed near a jaw portion of a sewing machine body  1 , a spreader mechanism  4  detachably attached to the top covering shaft mechanism  2  from below, an operating member  6  attached to the spreader mechanism  4 , a plurality of needles  10  respectively having an eye through which a corresponding needle thread is inserted and are vertically moved by a sewing machine motor to insert the needle threads into a workpiece, a presser  11  disposed below the needles  10  to press the workpiece against a throat plate, and thread guides  12 ,  13  which guide a covering thread to the spreader mechanism  4 . The operating member  6  is rotatable between a position at which the spreader mechanism  4  is locked with respect to the top covering shaft mechanism  2  and another position at which the spreader mechanism  4  is detachable from the top covering shaft mechanism  2 . 
     Top Covering Shaft Mechanism 
     As shown in  FIGS. 1 to 5 , the top covering shaft mechanism  2  includes a top covering shaft  21  downwardly extending from a lower portion of the jaw portion of the sewing machine body  1 , and an engaging base  22  through which the top covering shaft  21  is inserted. The top covering shaft  21  has a cylindrical shape. A lower end portion of the top covering shaft  21  is formed as a tapered portion  23  which is inclined with respect to an axial direction of the top covering shaft  21  such that a section area is gradually reduced toward a lower end thereof. The top covering shaft  21  is inserted through the engaging base  22  from above such that the tapered portion  23  downwardly projects from a lower end face of the engaging base  22  and a cylindrical portion of the top covering shaft  21  is surrounded by an inner wall of the engaging base  22 . 
     The engaging base  22  has a protrusion  24  which protrudes outward from a lower end portion of a side face of the engaging base  22 . The protrusion  24  has a semicircular shape when seen from a front, and an arcuate portion thereof is on an upper side of the protrusion  24 . When attaching the spreader mechanism  4  to the top covering shaft mechanism  2 , the operating member  6  engages with the protrusion  24  to prevent the spreader mechanism  4  from dropping off. 
     The lower end face of the engaging base  22  is formed with a concave portion  25  which is downwardly opened. A side face of the engaging base  22  is formed with a screw hole  26  into which a first setscrew  27  is screwed to fix the engaging base  22  to the top covering shaft  21 . More specifically, as shown in  FIG. 4 , a fixing groove  28  is formed on an outer circumferential surface of the top covering shaft  21  to extend in the axial direction thereof, and a tip end of the first setscrew  27  is pressed against the fixing groove  28  to fix the engaging base  22  to the top covering shaft  21 . Accordingly, it is possible to adjust a position of the engaging base  22  with respect to the axial direction of the top covering shaft  21  depending on a position at which the first setscrew  27  is pressed against the fixing groove  28 . 
     Spreader Mechanism 
     As shown in  FIGS. 1 ,  2 ,  4  and  5 , the spreader mechanism  4  includes a spreader  41  which catches the covering thread to interlace the covering thread with the needle threads, and a spreader support base  42  supporting the spreader  41 . The spreader  41  is a rod-like member, and is bent at a plurality of portions thereof. The spreader  41  has a pawl portion at a tip end portion thereof to catch the covering thread. The spreader  41  is rotatably inserted through the spreader support base  42  so as to be slidable in the vertical direction so that and a rotational position and a height of the spreader  41  can be adjusted. 
     The spreader support base  42  has a receiving portion  43  into which the top covering shaft  21  is fitted such that the tapered portion  23  is accommodated inside the receiving portion  43  so as to contact the receiving portion  43 . 
     An upper end face of the spreader support base  42  is formed with a convex portion  44  which is fittable in the concave portion  25  of the engaging base  22 . The convex portion  44  horizontally extends along the upper end face of the spreader support base  42 . 
     The spreader support base  42  is formed with a through hole  45  penetrating from the upper end face to a lower end face thereof. The spreader  41  is rotatably inserted into the through hole  45  so as to be slidable in the vertical direction. A screw hole  46  is formed on a side face of the spreader support base  42  toward the through hole  45 . A second setscrew  47  is screwed into the screw hole  46 , and a tip end of the second setscrew  47  is pressed against an outer circumferential surface of the spreader  41  to fix the spreader  41  to the spreader support base  42 . Accordingly, it is possible to adjust a position of the spreader  41  with respect to the spreader support base  42  depending on a position at which the second setscrew  47  is pressed against the outer peripheral surface of the spreader  41 . 
     The operating member  6  is rotatably attached to a front face of the spreader support base  42  with a setscrew  61 . The operating member  6  is rotatable between the position at which the spreader mechanism  4  is locked with respect to the top covering shaft mechanism  2  and the other position at which the spreader mechanism  4  is detachable from the top covering shaft mechanism  2 . 
     The spreader support base  42  is formed with another through hole  48  penetrating from the front face to a rear face thereof. A locking member  49  is provided in the through hole  48 . The locking member  49  has a tip portion, and is movable between a position at which the tip portion projects from the front face of the spreader support base  42  to fit in the operating portion  6  and another position at which the tip portion is disengaged from the operating member  6 . The locking member  49  is constantly biased by a spring  50  (an elastic member) in a direction in which the tip portion projects from the spreader support base  42  toward the operating member  6 . A rear end portion of the locking member  49  is attached to the rear face of the spreader support base  42  via an E-ring  51  so that it is prevented from slipping out of the through hole  48 . 
     A stopper  52  is arranged on the front face of the spreader support base  42  to regulate the rotation of the operating member  6 . More specifically, the stopper  52  is arranged such that the stopper  52  contacts the operating member  6  to block the rotation of the operating member  6  only when the operating member  6  is rotated to a position at which the operating member  6  and the protrusion  24  are disengaged from each other so that the spreader mechanism  4  becomes detachable from the top covering shaft mechanism  2 . 
     Operating Member 
     As shown in  FIGS. 1 ,  2  and  5 , the operating member  6  is rotatably attached to the front face of the spreader support base  42  with the setscrew  61 . The operating member  6  engages with the protrusion  24  to prevent the spreader mechanism  4  from dropping off from the top covering shaft mechanism  2 . When the operating member  6  is disengaged from the protrusion  24 , the spreader mechanism  4  becomes detachable from the top covering shaft mechanism  2 . 
     More specifically, the operating member  6  has a hook portion  62  which is engageable with the protrusion  24  to lock the spreader mechanism  4  to the top covering shaft mechanism  2 . The hook portion  62  has such a shape as to be hung on an upper side of the protrusion  24  when it is engaged with the protrusion  24 . That is, the hook portion  63  of the operating member  6  restricts a downward movement of the spreader mechanism  4  to prevent the spreader mechanism  4  from dropping off the top covering shaft mechanism  2 . 
     The operating member  6  is formed with a locking hole  63 . When the hook portion  62  is engaged with the protrusion  24 , the tip portion of the locking member  49  projects out from the spreader support base  42  by the elastic force of the spring  50  and is fitted in the locking hole  62  to securely lock the spreader mechanism  4  to the top covering shaft mechanism  2 . In a state in which the locking member  49  is not fitted in the locking hole  63 , accordingly, the operating member  6  is rotatable until it hits the stopper  52 . 
     The operating member  6  has a tab  64  adapted to be operated by a user. More specifically, the user holds the tab  64  when rotating the operating member  6 . 
     Attaching and Detaching of Spreader Mechanism 
     When attaching the spreader mechanism  4  to the top covering shaft mechanism  2 , the spreader mechanism  4  is attached to the top covering shaft mechanism  2  from below. At this time, the top covering shaft  21  is fitted in the receiving portion  43  of the spreader support base  42 , and the convex portion  44  of the spreader support base  42  is fitted in the concave portion  25  of the engaging base  22 . Then, the operating member  6  is rotated clockwise around the setscrew  61  by operating the tab  64  to prevent the spreader mechanism  4  from dropping. More specifically, as shown in  FIG. 6 , by rotating the operating member  6 , the hook portion  62  of the operating member  6  engages with the protrusion  24 , and the locking member  49  is fitted in the locking hole  63  of the operating member  6 , so that the spreader mechanism  4  is fixed to the top covering shaft mechanism  2 . Whether the spreader mechanism  4  is completely attached to the top covering shaft mechanism  2 , i.e., whether the operating member is rotated until the hook portion  62  engages with the protrusion  24 , can be confirmed by a visually checking the locking member  49  fitted in the locking hole  63 . 
     When the spreader mechanism  4  is completely attached to the top covering shaft mechanism  2 , the engagement of the top covering shaft  21  and the receiving portion  43  restricts the spreader mechanism  4  from moving in a plane orthogonal to the axial direction of the top covering shaft  21  and in an upward direction along the axial direction of the top covering shaft  2 . Moreover, the engagement of the protrusion  24  and the hook portion  62   a  restricts the spreader mechanism  4  from moving in a downward direction along in the axial direction of the top covering shaft  21 , and the engagement of the concave portion  25  and the convex portion  44  restricts the spreader mechanism  4  from rotating. Furthermore, the engagement of the locking member  49  and the locking hole  63  restricts the operating member  6  from rotating. 
     When detaching the spreader mechanism  4  from the top covering shaft mechanism  2 , the locking member  49  is inwardly pressed against the elastic force of the spring  50  to allow the rotation of the operating member  6 . In this state, the operating member  6  is rotated counterclockwise around the setscrew  61  be operating the tab  64 . By the rotation of the operating member  6 , the hook portion  62  is disengaged from the protrusion  24  so that the spreader mechanism  4  becomes detachable from the top covering shaft mechanism  2 . Since the locking member  49  cannot engage with the operating member  6  at portions other than the locking hole  63 , the locking member  49  does not interrupt the rotation of the operating member  6  during the rotation. Eventually, as shown in  FIG. 7 , the operating member  6  hits the stopper  52 , whereby the rotation of the operating member  6  is blocked. At this time, the hook portion  62  is completely disengaged from the protrusion  24  so that the spreader mechanism  4  can be detached from the top covering shaft mechanism  2 . 
     According to the sewing machine  100  of the exemplary embodiment described above, the engagement of the hook portion  62  and the protrusion  24  prevents the spreader mechanism  4  from falling from the top covering shaft mechanism  2 . That is, unlike the related art, the spreader mechanism  4  is not held by an elastic fitting structure. Therefore, there is no drawback that the elasticity of a plastic member deteriorates with the usage which causes an unstable holding of the spreader. 
     Further, a user can attach or detach the spreader mechanism  4  with respect to the top covering shaft mechanism  2  only by rotating the operating member  6  between two positions. Thus, as compared with the screwing operation or the like in the related art, it is possible to attach or to detach the spreader  41  more easily and smoothly. 
     Further, the tapered portion  23  of the top covering shaft  21  fits into the receiving portion  43  so as to contact with each other. Therefore, it is possible to accurately position the spreader  41  with respect to the top covering shaft  21  and to prevent a play in the coupling portion of the spreader mechanism  4  and the top covering shaft mechanism  2 . 
     Further, the convex portion  44  fits into the concave portion  25 . Thus, it is possible to easily position the spreader mechanism  4  with respect to the top covering shaft mechanism  2  in a rotational direction around the top covering shaft  21 . Furthermore, the engagement of the convex portion  44  and the concave portion  25  prevents the spreader mechanism  4  from rotating with respect to the top covering shaft mechanism  2 . Therefore, it is possible to ensure a torque transmission from the top covering shaft  21  to the spreader mechanism  4 . 
     Further, when attaching the spreader mechanism  4  to the top covering shaft mechanism  2 , the locking member  49  enters the locking hole  63  to prevent the rotation of the operating member  6 , thereby locking the spreader mechanism  4  to the top covering shaft mechanism  2 . On the other band, when rotating the operating member  6  to detach the spreader mechanism  4  from the top covering shaft mechanism  2 , the locking member  49  is pushed in against the elastic force of the spring  50  to disengage the locking member  49  from the operating member  6 , thereby unlocking t the spreader mechanism  4  from the top covering shaft mechanism  2 . Accordingly, it is possible to easily release the spreader mechanism  4  from the top covering shaft mechanism  2  by a simple operation of pushing the locking member  49 . 
     The position of the engaging base  22  with respect to the top covering shaft  21  is adjustable by loosing the first setscrew  27 . The engaging base  22  is fixed to the top covering shaft  21  with the first setscrew  27  such that, when the locking member  49  is fitted in the locking hole  63 , the hook portion  62  of the operating member  6  engages with the protrusion  24  without a clearance there between. On the other hand, the position of the spreader  41  with respect to the spreader support base  42  is adjustable with the second setscrew  47 . Therefore, the relative position of the spreader  41  with respect to the needles can be easily adjusted independently from other adjustments. 
     Further, whether the spreader mechanism  4  is completely attached to the top covering shaft mechanism  2  can be confirmed by visually observing the locking member  49  through the locking hole  63 . Therefore, it is possible to facilitate the attaching work. 
     Further, in a state in which the spreader mechanism  4  is detached, components related to the spreader  41  and disposed around the jaw portion of the sewing machine body  1  are only the top covering shaft  21  and the engaging base  22 . Therefore, when carrying out a sewing work without the spreader  41 , it is possible to provide a large space around the jaw portion of the sewing machine body  1 , thereby enhancing working efficiency, e.g., allowing an easy handling of a cloth. 
     Modifications 
     The present invention is not limited to the exemplary embodiment described above. For example, the operating member  6  may be attached to the top covering shaft mechanism  2  and the protrusion  24  may be formed on the spreader mechanism  4 . 
     Further, the concave portion  25  may be formed on the spreader support base  42  and the convex portion  44  may be formed on the engaging base  22 . 
     Further, the locking member  49  may be configured to project from the engaging base  22  and the locking hole  63  may be formed at another portion of the operating member  6  corresponding to the locking member  49 . 
     While description has been made in connection with an exemplary embodiment of the present invention and some modifications thereof, those skilled in the art will understand that various changes and other modification may be made therein without departing from the present invention. It is aimed, therefore, to cover in the appended claims all such changes and modifications falling within the true spirit and scope of the present invention.