Abstract:
An apparatus for lifting the presser foot of an embroidery machine includes an arm having an upper shaft providing a driving force, a presser foot driving cam mounted on the upper shaft, a transmission member coupled to the presser foot driving cam and making an oscillating motion, a presser foot driving lever connected to the transmission member and pivoting around a predetermined pivoting point thereof in a vertical direction, a presser foot driving block reciprocating along a needle bar guide shaft according to an amount that the presser foot driving lever is pivoted and moving the presser foot in a vertical direction, and a presser foot height adjustor, displacing the pivoting point of the presser foot driving lever to adjust a height of the presser foot.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates, in general, to an embroidery machine and, more particularly, to an apparatus for lifting the presser foot of an embroidery machine. 
         [0003]    2. Description of the Related Art 
         [0004]    Generally, an embroidery machine is a biaxial positioning control machine in which an embroidery stitch frame for fixing fabric undergoes horizontal motion in x-axis and y-axis directions while a needle bar thereof moves up and down. 
         [0005]    Since this embroidery machine does needlework while the embroidery stitch frame fixing the fabric is transferred in x-axis and y-axis directions, the precise and constant-speed movement of the embroidery frame has a close relationship to the quality of an embroidered pattern. 
         [0006]    Thus, as a source of power for driving the needle bar of the embroidery machine in a vertical direction, a servo motor, an induction motor capable of controlling speed, or the like is used. As the power source for transferring the embroidery stitch frame in x-axis and y-axis directions, a stepping motor, ensuring good positioning and easy control, is typically used. 
         [0007]    The embroidery machine has a sewing frame movably installed on a table, and comprises a lifting mechanism, in which, during sewing, a presser foot, described below, is supported at the bottom dead point and moves the presser foot back to the top dead point, which is higher than the bottom dead point. 
         [0008]      FIG. 1  is a perspective view illustrating one example of an embroidery machine, and  FIG. 2  is a perspective view illustrating the driving structure of a presser foot in a known embroidery machine. As illustrated in  FIG. 1 , an embroidery machine  1  has a plurality of heads, which is installed at the front thereof in a longitudinal direction. Each head includes a needle bar supporting case  4 , which is provided with a plurality of presser feet  5  (each of which is a member used to press a sewing material such as a sheet of cloth to be sewn), at the front of an arm  3 . 
         [0009]    As illustrated in  FIG. 2 , each presser foot  5  is adapted to cooperate with a needle bar  8  so as to pivot in a vertical direction. A motor (not shown), providing power, is installed below one side of a table of the embroidery machine, and is connected to a controller for controlling sewing operation. The motor is connected with an upper shaft  6 , which provides driving force and passes through the arm  3  in a horizontal direction. 
         [0010]    Further, a driving cam  10  for the presser foot is mounted on the upper shaft  6 . The driving cam  10  is coupled with a transmission member, which is made up of a cam roller  9  and a driving lever  11  for the presser foot, in an orbital groove thereof. Thus, the transmission member makes an oscillating motion, and pivots around a predetermined pivoting point in a vertical direction. 
         [0011]    In addition, a needle bar guide shaft  7  is mounted on the arm  3  in a vertical direction. A needle bar  8  is installed parallel to the needle bar guide shaft  7 , and passes through the head  4  in a vertical direction. The presser foot  5  is coupled to the lower end of the needle bar  8 . 
         [0012]    A driving block  13  for the presser foot is fitted around the needle bar guide shaft  7 , so that the driving block  13  reciprocates along the needle bar guide shaft  7  in proportion to the amount that the driving lever  11  is pivoted, and thus moves the presser foot  5  in a vertical direction. 
         [0013]    At this time, it is difficult to adjust the height at which the presser foot  5  is placed on the sewing material because it is bent in a stepped shape at a predetermined length when viewed overall. 
         [0014]    Further, in order to adjust the position of the presser foot  5 , the parts of the head  4 , such as a head cover plate (not shown), must be removed. Reference numeral  12 , which has not yet been described, indicates a driving lever connecting link for the presser foot. 
       SUMMARY OF THE INVENTION 
       [0015]    Accordingly, the present invention has been made to solve the foregoing problems with the related art, and the present invention is intended to propose an apparatus for lifting a presser foot of an embroidery machine, which can adjust the height of the presser foot. 
         [0016]    Another object of the present invention is to provide an apparatus for lifting a presser foot of an embroidery machine, which easily replaces a sewing material or a sewing frame when replaced. 
         [0017]    In order to achieve the above objects, according to one aspect of the present invention, there is provided an apparatus for lifting the presser foot of an embroidery machine, which includes an arm having an upper shaft providing a driving force; a presser foot driving cam mounted on the upper shaft; a transmission member coupled to the presser foot driving cam and making an oscillating motion; a presser foot driving lever connected to the transmission member and pivoting around a predetermined pivoting point thereof in a vertical direction; a presser foot driving block reciprocating along a needle bar guide shaft according to an amount that the presser foot driving lever is pivoted and moving the presser foot in a vertical direction; and a presser foot height adjustor, which displaces the pivoting point of the presser foot driving lever so as to adjust the height of the presser foot. 
         [0018]    According to an embodiment of the present invention, the presser foot height adjustor includes a driving motor, generating the driving force, a driving pulley, rotatably coupled to the driving motor, a driven pulley, pivotably coupled to the driving pulley, an eccentric member, installed on the driven pulley, and a presser foot driving lever, hinged to the eccentric member at a pivoting point thereof. 
         [0019]    According to another embodiment of the present invention, the apparatus further comprises a cylindrical supporting means for an eccentric member, which is connected to the driven pulley and has a hole through which the eccentric member passes. 
         [0020]    According to a further embodiment of the present invention, the eccentric member includes large and small spindles on opposite sides of a circular body thereof, the small spindle being connected in a hinge hole of the presser foot driving lever, and the large spindle passing through the supporting means to be connected to the driven pulley. 
         [0021]    According to another embodiment of the present invention, the presser foot height adjustor adjusts the height of a bottom dead point of the presser foot according to the thickness of the sewing material. 
         [0022]    According to yet another embodiment of the present invention, the presser foot height adjustor adjusts the height of the bottom dead point of the presser foot to a programmed height according to the thickness of the sewing material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
           [0024]      FIG. 1  is a perspective view illustrating one example of an embroidery machine; 
           [0025]      FIG. 2  is a perspective view illustrating the driving structure of a presser foot in a known embroidery machine; 
           [0026]      FIG. 3A  is a perspective view illustrating the state in which an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the present invention is installed; 
           [0027]      FIG. 3B  is an enlarged view illustrating part “A” of  FIG. 3A ; 
           [0028]      FIG. 4  is an exploded perspective view illustrating an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the present invention; 
           [0029]      FIG. 5A  is a partial perspective view illustrating the state in which an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the present invention is installed; 
           [0030]      FIG. 5B  is an enlarged view illustrating part “B” of  FIG. 5A ; and 
           [0031]      FIG. 6  is a side view illustrating the operation of an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    Reference will now be made in greater detail to an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the invention with reference to the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
         [0033]      FIG. 3A  is a perspective view illustrating the state in which an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the present invention is installed, and  FIG. 3B  is an enlarged view illustrating part “A” of  FIG. 3A .  FIG. 4  is an exploded perspective view illustrating an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the present invention. 
         [0034]    Further,  FIG. 5A  is a partial perspective view illustrating the state in which an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the present invention is installed, and  FIG. 5B  is an enlarged view illustrating part “B” of  FIG. 5A .  FIG. 6  is a side view illustrating the operation of an apparatus for lifting the presser foot of an embroidery machine according to an exemplary embodiment of the present invention. Referring to the drawings, the apparatus for lifting the presser foot of an embroidery machine according to the present invention comprises a height adjustor for a presser foot, which displaces the pivoting point of a presser foot driving lever to adjust a height of the presser foot. 
         [0035]    The presser foot height adjustor functions to displace the pivoting point of the presser foot driving lever to adjust the height of the presser foot. To this end, as illustrated in  FIGS. 3A and 4 , the presser foot height adjustor comprises a driving motor, a driving pulley rotatably coupled to the driving motor, a driven pulley pivotably coupled to the driving pulley, an eccentric member installed on the driven pulley, and a presser foot driving lever hinged to the eccentric member at a pivoting point thereof. 
         [0036]    As illustrated in  FIGS. 3A and 4 , the driving motor  40  has a protruding shaft on one side thereof, and is fastened to one side of an arm  23  through a connecting bracket  41 , which is connected to a motor case housing of the driving motor  40  and has a C-shaped cross-section when viewed from the side of the motor case, using screws (not shown). 
         [0037]    Further, the driving pulley  42  is coupled to the shaft of the driving motor  40 , and is connected to the driven pulley  43 , which has a relatively greater diameter, through a belt  46 . The eccentric member  45  passes through a cylindrical supporting means  44  having a hole  44   a , and is installed on the driven pulley  43 . 
         [0038]    In the present invention, the driving pulley  42  and the driven pulley  43  are connected with each other through the belt  46 . Alternatively, the driving pulley  42  and the driven pulley  43  may be engaged with each other. 
         [0039]    As illustrated in  FIG. 4 , the eccentric member  45  includes large and small spindles on opposite sides of a circular body  45   a . The small spindle  45   b  protrudes from an edge of the body  45   a , which is displaced from the center of the body  45   a , and is connected in a hinge hole  31   a  of the presser foot driving lever  31 . The large spindle  45   c  passes through the supporting means  44  and the driven pulley  43  in series. 
         [0040]    As illustrated in  FIG. 4 , the presser foot driving lever  31  has an obtuse V shape, includes the hinge hole  31   a  in the middle thereof and large and small through-holes  31   b  and  31   c  in opposite ends thereof, and is hinged to the eccentric member  45  through the hinge hole  31   a.    
         [0041]    As for a transmission member of the prevent invention, which is equivalent to the transmission member constituted of the cam roller  9  and the presser foot driving lever  11 , as illustrated in  FIG. 2 , a presser foot driving cam  30  is coupled to the outer circumference of the upper shaft  26 , as illustrated in  FIG. 4 . An arm protruding from the outer circumference of the presser foot driving rod  30  is connected to the through-hole  31   b  of the presser foot driving lever  31 , and the through-hole  31   c  of the presser foot driving lever  31  is connected with a stub  34   a  of one end of a presser foot connecting link  34 , as illustrated in  FIG. 3B . The other end of the presser foot connecting link  34  is fixedly coupled to one side of a presser foot driving block  33 , which slides on a guide shaft  27  ( FIG. 3A ) for the needle bar in a vertical direction. 
         [0042]    Further, the presser foot driving block  33  is provided therein with a presser foot connecting holder  37  ( FIG. 5B ), which drives a presser foot driving holder  36 , which is installed so as to be able to slide on the outer circumference of the needle bar  28 . Thereby, the presser foot driving shaft  32 , which is installed parallel to the needle bar  28  under the presser foot driving holder  36 , moves up and down, and thus the presser foot  25 , installed below the presser foot driving shaft  32 , moves up and down. 
         [0043]    The reference numeral  33  indicated in  FIGS. 3B ,  5 A and  6  is the presser foot driving block, which has the same configuration and driving mechanism as one (reference numeral  26 ) disclosed in Korean Patent Application No. 10-2007-0005680 (entitled Presser Foot Guide Structure of Embroidery Machine), which was filed by the present applicant. The configuration and driving mechanism of the presser foot  25  coupled to the presser foot driving block  33  are described in detail in the above-mentioned prior application and in an application (Korean Patent Application No. 10-2007-0020471, entitled Presser Foot Driving Structure of Embroidery Machine) that establishes the internal right of priority for this patent application, and so a detailed description thereof will be omitted. 
         [0044]    Now, the operation of the present invention having the above-mentioned configuration will be described. 
         [0045]    As illustrated in  FIG. 6 , when the upper shaft  26  is rotated by the driving force of the motor (not shown), the presser foot driving rod  30  rotates around the upper shaft  26 . Simultaneously, the presser foot driving block  33 , which is connected to the presser foot driving lever  31  through the connecting link  34 , repeats upward and downward movement. 
         [0046]    Further, the needle bar  28 , which is connected to the lower portion of the presser foot driving holder  36 , which is engaged with the presser foot driving block  33 , moves in the head  24  in a vertical direction, and the presser foot  25 , which is connected to the lower end of the presser foot driving shaft  32 , installed parallel to the needle bar  28 , also moves up and down. 
         [0047]    Meanwhile, in the case in which an attempt is made to raise the presser foot  25  to a predetermined height, as necessary, the driving pulley  42  is rotated by the counterclockwise operation of the driving motor  40 . This rotating force is transmitted to the driven pulley  43  through the belt  46 , and then to the presser foot driving lever  31  through the cylindrical supporting means  44  and the eccentric member  45 . 
         [0048]    Thus, the transmitted rotating force moves the presser foot driving block  33  upwards through the connecting link  34  connected to the presser foot driving lever  31 , and the needle bar  28  connected to the presser foot driving holder  36  engaged with the presser foot driving block  33  moves upwards. At this time, the presser foot  25  connected to the presser foot driving shaft  32  is also raised to a predetermined height. 
         [0049]    In contrast, in the case in which an attempt is made to lower the presser foot  25  to a predetermined height, the rotating force caused by clockwise operation of the driving motor  40  moves the presser foot driving block  33  downwards through the connecting link  34 , and the needle bar  28  connected to the presser foot driving holder  36  moves downwards. At this time, the presser foot  25  connected to the presser foot driving shaft  32  is also lowered. 
         [0050]    Thus, the apparatus for lifting the presser foot makes it possible to adjust the height of the bottom dead point of the presser foot  25  on the basis of the thickness of the sewing material. In other words, the pivoting point of the presser foot driving lever  31 , which is connected to the apparatus for lifting the presser foot, is displaced to make it possible to adjust the height of the presser foot  25 . In the case in which the sewing material is relatively thick, the height of the bottom dead point of the presser foot  25  is increased through the apparatus for lifting the presser foot. In contrast, in the case in which the sewing material is relatively thin, the height of the bottom dead point of the presser foot  25  is decreased through the apparatus for lifting the presser foot. Thereby, sewing is performed. 
         [0051]    Meanwhile, the driving motor  40  can be automatically controlled through a program that takes into account the thickness of the sewing material if necessary. For example, the embroidery sewing frame fixing the fabric is slightly transferred in x-axis and y-axis directions when a sewing pattern is input, and then the position at which the thickness of the sewing material is changed is checked manually. The position and the height from the needle plate (not shown) of the presser foot  25 , depending on the thickness of the sewing material at the position (or the number of driving pulses from the driving motor), are input as data. Alternatively, instead of the input data, the number of needles counted up to the position at which the thickness of the sewing material is changed may be set. 
         [0052]    With this configuration, when the presser foot reaches the position at which the thickness of the sewing material changes during sewing, a number of pulses (or a predetermined number of needles) is supplied according to the height input to the driving motor  40 . Thereby, the position of the bottom dead point of the presser foot  25  can be automatically controlled. 
         [0053]    As apparent from the above description, according to the present invention, the height of the presser foot can be adjusted according to the type and thickness of the sewing material. 
         [0054]    Further, when the sewing material or the sewing frame is replaced by an operator, the presser foot is manually or automatically displaced to the top dead point, which is higher than the bottom dead point. Thereby, the replacement can be easily performed. 
         [0055]    In addition, the trouble of removing the parts of the head, such as a head cover plate, in order to adjust the position of the presser foot, is eliminated. 
         [0056]    Although an exemplary embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.