Patent Publication Number: US-6904852-B2

Title: Sewing machine with needle holder of needle interval adjustable type

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a sewing machine with needle holder of needle interval adjustable type capable of varying the interval of plural needles by a needle holder. 
   2. Description of the Prior Art 
   A conventional sewing machine with needle holder of needle interval adjustable type was designed to adjust the interval of plural needles by rotating a sub needle holder (assistant needle holder) relatively to a main needle holder (needle holder main body) when loosening a set screw. See, for example, Japanese Utility Model Laid-open No. H3-103085 (page 1, FIG. 1). 
   However, in the conventional sewing machine with needle holder of needle interval adjustable type, in particular, when the fitting position of the sub needle holder is changed relatively to the main needle holder so as to expand the longitudinal width of the plural needles, the lateral width of the plural needles is also expanded, and specified sewing quality could not be obtained. 
   It is hence a primary object of the present invention to provide a sewing machine with needle holder of needle interval adjustable type capable of widening or narrowing the longitudinal width of plural needles without changing the lateral width. 
   SUMMARY OF THE INVENTION 
   A sewing machine with needle holder of needle interval adjustable type comprises a looper, a main needle holder, a sub needle holder, and a plurality of needles. The looper is fixed to a looper stand, and moves laterally beneath a needle plate. The main needle holder is disposed above the needle plate, and has a screw portion for fitting a needle bar. The sub needle holder is fitted to the main needle holder by a set screw so as to be adjustable in position. The plurality of needles are individually fitted to the needle holders, and penetrate through a needle hole of the needle plate when descending. In the sewing machine with needle holder of needle interval adjustable type, when loosening the set screw, the fitting position of the sub needle holder to the main needle holder is changed, and the interval of the plural needles can be widened or narrowed. 
   It is a feature of the present invention that a longitudinal slit is linearly formed in the main needle holder. A fitting position of the sub needle holder to the main needle holder is changed on the longitudinal slit, and cloth penetration lines by at least two needles of the plural needles are arranged in a narrow width. 
   According to the present invention, the fitting position of the sub needle holder to the main needle holder is changed along the longitudinal slit formed linearly on the main needle holder. Therefore, when extending the longitudinal width of the plural needles, the lateral width is indifferent, and the cloth penetration lines by at least two needles of the plural needles can be mutually set along in a narrow width. 
   In the present invention, preferably, the plural needles fitted to the needle holders are disposed at the sliding surface side of the longitudinal slit. Corresponding to the plural needles, a plurality of loopers may be provided, and the looper responsible for the needles of the sub needle holder is mounted on the looper stand through the looper holder so as to be adjustable in the longitudinal direction, and when changing the fitting position of the sub needle holder, the corresponding looper may be changed together. Further preferably, a guide piece may be provided at the lower side of the needle plate, and the needle hole of the needle plate may be partly blocked by the guide piece from the cloth feed direction. 
   In a preferred specific structure of the present invention, the longitudinal slit of the main needle holder is extended linearly forward from the main needle holder, and a concave sliding surface is provided at its left side. The longitudinal slit of the main needle holder has the sub needle holder, and this sub needle holder is slidably fitted to the concave sliding surface of the longitudinal slit. The sub needle holder is fixed by a set screw through a slot formed in the longitudinal slit. At the lower end of the main needle holder, a fitting hole for needle is opened, and the upper portion of the right needle is fixed in the right needle fitting hole. At the lower end of the sub needle holder, a fitting hole for needle is opened, and the upper portion of the left needle is fixed in the left needle fitting hole. By forming the needle fitting holes of the needle holders by deviating longitudinally, the cloth penetration lines by needles at the time of sewing are mutually set along in a narrow width. A plurality of loopers are disposed beneath the needle plate, and one looper is responsible for the right needle, and its base is mounted on the looper stand. Other looper is responsible for the left needle disposed ahead of the first looper, and its base is mounted on a looper holder. The looper holder has a sliding portion, and its sliding portion is fixed to the concave sliding surface formed in the looper stand by a screw. The looper holder is designed to slide longitudinally along the concave sliding surface of the looper stand when loosening the screw. The guide piece is fixed by a screw through a slot of the needle plate. Out of the needle holes in the needle plate, the needle hole for left needle penetration is partly blocked from the cloth feed direction by the guide piece of the needle holes of a presser foot disposed above the needle plate for pressing the cloth to the needle plate, the needle hole for left needle penetration is a slot, and after changing the position of the sub needle holder to the main needle holder, the left needle also penetrates through the slot. By recessing the top of the needle plate around the slot, the screw is prevented from projecting above the needle plate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an essential perspective view showing a sewing machine with needle holder of needle interval adjustable type according to the present invention. 
       FIG. 2  is a perspective exploded view showing needle holders of the sewing machine. 
       FIG. 3  is a schematic plan view showing essential parts of needle plate of the sewing machine. 
       FIG. 4  is a schematic plan view showing cloth penetration lines when sewing by the sewing machine. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings, a preferred embodiment of the present invention is described below.  FIG. 1  is an essential perspective view showing a sewing machine with needle holder of needle interval adjustable type according to the present invention. A needle plate  1  is fixed to a cloth platform  2  by a screw  3 , and both tops are on a same plane. A presser foot  4  is disposed above the needle plate  1 . The presser foot  4  is fixed to a pressure bar  5  by a screw  6 , and the pressure bar  5  is pressed down by a coil spring (not shown) disposed in a sewing machine arm. That is, the presser foot  4  presses the cloth to the needle plate  1 . Beneath the needle plate  1 , a known feed dog (not shown) is disposed. The feed dog intermittently comes in and out from the slit of the needle plate, and cooperates with the presser foot  4  when the feed dog comes out, so that the cloth is conveyed in cloth feed direction F. 
   Above the needle plate  1 , a needle stub  7  is disposed. The needle stub  7  is composed of a main needle holder  8  and a sub needle holder  9 . The main needle holder  8  has, as shown in  FIG. 2 , a screw portion  8   a  for mounting a needle bar, and the screw portion  8   a  fitted into the lower end of the needle bar  10 . The main needle holder  8  also has a longitudinal slit  11 . The longitudinal slit  11  is extended linearly forward from the main needle holder  8 , and it has a concave sliding surface  11   a  at the left side. A fitting hole for needle is opened at the lower end of the main needle holder  8 , and the upper part of a right needle  12  is fixed in the fitting hole for right needle. 
   A sub needle holder  9  is disposed in the longitudinal slit  11  of the main needle holder  8 . This sub needle holder  9  is slidably fitted to the concave sliding surface of the longitudinal slit  11 , and it is fixed by a set screw  14  through a slot  11   b  formed in the longitudinal slit  11 . A fitting hole for needle is opened at the lower end of the sub needle holder  9 , and the upper part of a left needle  13  is fixed in the fitting hole for left needle. The plural needles  12 ,  13  fitted to the needle holders  8 ,  9  are disposed at the side of the sliding surface  11   a  of the longitudinal slit  11 . The needle bar  10  is driven to slide vertically by a known needle driving device installed in a sewing machine arm, and when the needles  12 ,  13  descend, they penetrate through the needle holes of the presser foot  4  and needle plate  1 . By forming the needle fitting holes of the needle holders  8 ,  9  by deviating longitudinally, as shown in  FIG. 4 , cloth penetration lines L 1 , L 2  by the needles  12 ,  13  at sewing can be set along with each other in a narrow width. 
   Plural loopers  15 ,  16  are disposed beneath the needle plate  1 . One looper  15  is responsible for the right needle  12 , and its base is fitted to a looper stand  17 . The looper stand  17  is fixed to an oscillating shaft  18  by a screw  19 . The oscillating shaft  18  cooperates with rotation of the main shaft of the sewing machine (not shown), and oscillates in a direction intersecting with the cloth feed direction F (moves laterally). Other looper  16  is disposed ahead of the looper  15 . The looper  16  is responsible for the left needle  13 , and its base is fitted to a looper holder  20 . The looper holder  20  has a sliding portion  20   a , and the sliding portion  20   a  is fixed to a concave sliding surface formed in the looper stand  17  by a screw  20   b . The looper holder  20  is slidable back and forth along the concave sliding surface of the looper stand  17  when the screw  20   b  is loosened. That is, the looper  16  responsible for the needle  13  of the sub needle holder is fitted to the looper stand  17  through the looper holder  20  so as to be adjustable in longitudinal position. 
   At the lower side of the needle plate  1 , a guide piece  21  is attached as shown in FIG.  3 . The guide piece  21  is fixed by a screw  22  through a slot  1   a  of the needle plate  1 . Out of the needle holes  1   b ,  1   c  of the needle plate, the needle hole  1   b  for penetration of the left needle  13  is partly blocked by guide piece  21  from the cloth feed direction F. Out of the needle holes in the presser foot, a needle hole  23  for penetration of the left needle  13  is a slot. After change of the position of the sub needle holder  9  to the main needle holder  8 , the left needle  13  penetrates through the slot  23 . By recessing the top of the needle plate around the slot  1   a , the screw  22  is prevented from projecting above the needle plate  1 . This is a structure for preventing interference of cloth conveyance.