Abstract:
A device for operating several sewing functions is provided with a single control disk with curved paths arranged peripherally and facially on the control disk for acting radially and axially. The control disk is driven by a stepper motor and allows individual or several functions to be executed during the rotary movement as well as temporarily stopping others.

Description:
BACKGROUND  
       [0001]     The invention relates to a device for operating several functions of a sewing machine.  
         [0002]     In order to increase the sewing comfort, modern sewing and knitting machines are provided with a multitude of partially or fully automated functions previously performed by hand. Individual functions can be triggered by operating a lever or a push button. Other functions need to be performed temporarily exactly adjusted to one another, in order to avoid collisions of machinery parts or the like. On the one hand, appropriate supervisory, safety, and control means are necessary, and, on the other hand, the respective mechanical drives for performing the individual functions are also required. Individual drives can be used, which control the allocated functions. This leads to higher production costs and a correspondingly high control and space requirement within the machine housing.  
       SUMMARY  
       [0003]     The object of the present invention is to provide a device, which allows several functions to be simultaneously performed and/or performance in a synchronized manner and/or to interrupt the functions intermittently using a single drive element.  
         [0004]     This object is attained in a device with the features according to the invention. Advantageous embodiments of the invention are described below.  
         [0005]     Using a cam disk, which is provided with curved paths not only peripherally but also at its faces, which act both radially as well as axially, drive functions can be superimposed and/or temporarily switched on and/or interrupted through a certain turning range. A particularly advantageous embodiment of the invention allows triggering of functions with a single cam disk or control disk, ranging over a rotation of more than 360° on the shaft supporting the control disk. All functions can therefore be performed on the very same shaft and powered by a single drive. The individual functions are automatically performed at a synchronized progression so that faulty manipulations, which might result in damages of the sewing machine, are excluded. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     Using the illustrated exemplary embodiment for three functions the invention is explained in greater detail. Shown are:  
         [0007]      FIG. 1  is a schematic view of a domestic sewing machine with a partial section of the lower arm in the area of the hook;  
         [0008]      FIG. 2  is a path/time diagram of three sewing functions;  
         [0009]      FIG. 3  is a side view of a control disk;  
         [0010]      FIG. 4  is a cross-section through a control disk along a line IV-IV in  FIG. 3 ;  
         [0011]      FIG. 5  is a cross-section through a control disk along a line V-V in  FIG. 3 ;  
         [0012]      FIG. 6  is an axial view of the control disk from the direction of the arrow VI in  FIG. 3 ;  
         [0013]      FIG. 7  is a perspective representation of the drive organs for a thread cutter;  
         [0014]      FIG. 8  is a perspective representation of the drive elements and the operational elements for a lowering motion of the transporter,  
         [0015]      FIG. 9  is a perspective representation of the drive elements for locking the hook; and  
         [0016]      FIG. 10  is a perspective view of the lowering device for the transporter. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]     In the schematic representation according to  FIG. 1 , only the elements in a domestic sewing machine  1  necessary for understanding the invention are shown and briefly described.  
         [0018]     A drive motor M is arranged in the machine housing  3 , which drives the hook  9  and the transporter  11  via a primary shaft  5  in the lower arm  7 . The drive of the needle rod  15  occurs via an upper drive  13 . Furthermore, a control disk  17  is used in the lower arm as an element performing a multitude of functions. In the following, the construction and the functions of the control disk  17  are explained in greater detail.  
         [0019]     The control disk  17  according to  FIG. 3  comprises a central pivot bearing, e.g., in the form of a bushing  19  and a peripherally arranged sprocket  21  for driving the control disk  17 . Alternatively, the drive of the control disk  17  may also occur by a drive, which is connected to a shaft in a form-fitting manner, itself fixed to the control disk  17 , or with a rotary motor, with its rotor being formed by the control disk  17  and its stator by a fixed shaft. Both alternative embodiments are not shown.  
         [0020]     At the first face  23  of the control disk  17  (cf.  FIG. 4 ) a guide groove  25  is provided, partially circular and partially helical, which extends over an angle of more than 360°; in the present example over an angle of approximately 540°. The guide groove  25  extends over the first 270° with a constant radius, i.e. circular. The subsequent angular range of approximately 270° extends helically, i.e. the radius essentially reduces continuously. A control pin  27  engaging the guide groove  25  remains therefore in the first guiding section with a constant radius in its original position x o  and it does not move. Only at another rotary movement counter clock- wise the control pin is guided out of the original position x o  into the intermediate position x 1  and further into the final position x 2 . Depending on the change of the radius of the groove  25  per angular unit the progression of the movement of the machine elements connected to the control pin  27  can be determined. The control pin  27  is connected to a slide bar  35 , not shown in  FIG. 4 , but discernible in  FIG. 7 . A suitable horizontal guidance  29  for said slide bar  35  is also discernible in  FIG. 7 . The horizontal guidance  29  is not transferred by the control pin  27  but by a guide pin  31 . For this purpose, a horizontal guide groove  29  is recessed in a carrier  33 , which carrier  33  also supports the hook  9 .  
         [0021]     The control pin  27  and the guide pin  31  are connected to the slide bar  35 , which at its front end  36  has an angled toothed segment  37  arranged pivotal on the carrier  33 . The toothed segment  37  engages the rear, toothed end  40  of a thread cutting device  39  in a comb-like manner. The cutting edge  41  at the front end  42  of the thread cutting device  39  contacts laterally of the thread exit opening  44  of the hook  9 .  
         [0022]     Using the thread cutting device  39 , the bottom thread can be cut at a suitable distance from the thread exit opening  44 . The end of the thread extending out of the hook  9  is still provided with a length sufficient for ensuring the sewing of new fabric to be sewn.  
         [0023]     In another embodiment of the thread cutting device  39 , the upper thread can also be cut. The operation of the thread cutting device  39  is not an object of the present invention and therefore it is not explained in greater detail, here. In the following, the thread cutting device will be described in greater detail and together with the two other functions of the control disk  17 .  
         [0024]     In the example shown, the hook  9  is supported on a rotational axis G on the carrier  33  such that it can be rotated and driven. The drive of the hook  9  is not shown, because in  FIG. 7  it is covered by the carrier  33 . In this embodiment of the invention, the hook  9  is pivotal around a pivotal axis S vertically arranged in reference to the rotational axis G of the hook  9 , in order to optimally design the bobbin exchange of the bottom thread for the operating personnel. For the bobbin exchange of the bottom thread the hook  9  pivots from the operational position shown in  FIG. 7  into a thread bobbin-removal position, pivoted by approximately 180°. In other words, the face of the thread hook  43  seen in  FIG. 7  is positioned, after the pivotal motion, at the rear side of the carrier  33  and is freely accessible from the front side of the sewing machine  1  by the person sewing.  
         [0025]     In  FIG. 5 , a control curve  45  is discernible that is kidney-shaped and peripheral on the control disk  17 . A sensor finger  47  represented by a black dot in the cross-section is moved, based on the curved form, during the rotation of the control disk  17  from an original position y 0  into an end position y 1  and back into the original position y 0 . Here, in the exemplary embodiment shown, the entire horizontal shift occurs already by an angular rotation of approximately 75° in a positive and negative rotary direction.  
         [0026]     The sensor finger  47  engaging the control curve  45  is arranged at the rear end  48  of a lifting rod  49  positioned horizontally on the carrier  33  supported in a shiftable manner (cf.  FIG. 8 ). The lifting rod  49  is longitudinally guided, for example, at two threaded screws  51 ,  53 , which penetrate the lifting rod  49  in two oblong holes. A tensile spring  60  suspended at the lifting rod  49  serves to continuously press the sensor finger  47  firmly against the control curve  45 . The front end  50  of the lifting rod  49  engages at a lowering element  59  for the transporter, known from prior art and not described in greater detail. Rotating the control disk  17  by approximately 75° causes the transporter  11  to be transferred form the operational position into a resting position, in which its teeth cannot extend beyond the surface of the stitching plate at the lower arm  7 .  
         [0027]     For clarification purposes, in  FIG. 10 a  conventional device for lowering the transporter  11  is shown in a perspective representation. The same reference characters are used as in the device according to the invention. Using a rotational knob  83 , with either a lever drive or a sprocket drive being arranged at its rear end (not shown), the lifting rod  49  at its one end is moved in the direction of the arrow q, at which the sensor finger  47  is arranged according to the invention. This movement causes a curved disk  87  to be displaced axially by a fork  85  formed at the opposite end of the lifting rod  49 , and thus it is guided out of the area of the sensor finger  89 , which is supported on the curved disk. This way, the transporter can pivot in the clockwise direction by a pivotal motion around a rotary axis X and thus arrives under the stitching plate at the lower arm  7  of the sewing machine. In  FIG. 8  it is further discernible, how a drive sprocket  61  below the sprocket  21  engages, which is supported on a drive motor  63  (see  FIG. 7 ). Using this drive motor  63 , e.g., a stepper motor, the control disc  17  is controlled by the sewing machine control via the sprocket  21 , and can be set in motion in the positive or negative rotational direction.  
         [0028]     On the control disk  17 , on the second face  65  visible in  FIGS. 8 and 9 , another three-dimensional control path  67  is provided. The latter serves to move a control rod  69  in a predetermined temporal progression in the longitudinal direction h and, at certain rotational angular sections of the control path  67 , also to move it in the axial direction in reference to the control curve (cf. arrows a). The control rod  69  contacts with its front end, embodied as a sensor head  72 , the peripheral control path  67 . The control rod  69  is continuously pressed against the peripheral control surface  73  by a tensile spring (not shown) suspended at a hook  71  (cf.  FIGS. 6 and 9 ). A second spring, not shown either, engages a second hook  74  and pulls the control rod  69  to the face of the control disk  17  and/or to the control path  75  acting axially at the face. Thus, the radially extending control path  67  causes a movement of the control rod  69  in the direction h and the facial control path  75  leads the control rod  69 , beginning at a certain rotational angle, out of the radial control path  67  so that, in spite of an additional rotation of the control disk  17 , no additional motion can occur in the direction h. The rear end  70  of the control rod  69  contacts a locking lever  77 . The locking lever  77  ensures that in its operational position the hook  9  is located exactly below the needle and is locked. In the bobbin exchange position the hook  9  is held by the locking mechanism.  
         [0029]     In the graphic representation in  FIG. 2 , the driving paths of the three individual elements caused by the rotation of the control disk  17  are shown depending on the rotational angle of the control disk  17 .  
         [0030]     In the drawing, the thick, continuous curve  135  shows the progression of the motion of the slide bar  35 , by which the cutting device for the bottom thread is activated. The curve  149  represented in dot-dash lines shows the progression of the lifting rod  49  for lowering the transporter and a finely drawn curve  169  shows the driving path of the control rod  69  for locking the pivotal motion of a carrier supported on the hook  9 .  
         [0031]     Based on this path/time-diagram according to  FIG. 2 , the function of the control disk  17  is explained in the following.  
         [0032]     If the operating person intends to work without the transporter  11  for the material drive, e.g., during quilting or mending, rotating the control disk  17  by a positive rotational angle of 70° can lower the transporter  11 . Here the two other functions, namely the thread cutting and the unlocking of the hook  9  are not activated, because during the rotational motion of the control disk  17  by approximately 70°, the control pin  27  for the thread cutting device  39  and the sensor head  72  for the hook lock are not moved by the control disk  17  over this rotary range (70°). Only the sensor finger  47  is displaced laterally out of the position y 0  into the position y 1  by the control curve  45 , with a kidney-shaped, and causes the lowering of the transporter  11  via the lifting rod  49 .  
         [0033]     If at the end of the sewing process the bottom thread and, depending on the embodiment of the thread cutting device  39  the upper thread as well, are to be cut, the control disk  17  is rotated in the negative direction, i.e. counter clock-wise, for example by 250°. Here, the slide bar rod  35  operates, driven by the control pin  27 , the cutting device  39  via the toothed segment  37 . Simultaneously, i.e. synchronized thereto, at the beginning of the rotational movement the transporter  11  is lowered because the sensor finger  47  is also shifted by the kidney-shaped control path  45 , in the negative rotational direction as well, out of the operational position into a resting position. The lowering of the transporter  11  is therefore advantageous for cutting threads as well, because here the guiding away of the material between the sewing foot and the stitching plate is not hindered by the teeth of the transporter  11 . Additionally, the threads cannot become caught in the transporter  11 .  
         [0034]     If prior or during the sewing process the bottom bobbin needs to be exchanged because the supply of bottom thread is used up or another thread is required, the rotation of the control disk  17  occurs in the positive rotational direction. During, for example, the first 70 degrees of the rotation the transporter  11  lowers again, because the sensor finger  47  is activated by the control curve  45 . The thread cutting device  39  is not activated by this rotary movement, because the control pin  27  is located in the guide groove section  25 , which has a constant radius. After crossing a rotary angle of, for example 70°, the sensor finger  47  also reaches the range of the control curve  45  having a constant radius for lowering the transporter. Therefore, no other movements occur.  
         [0035]     However, the control rod  69  and/or the sensor finger  47  positioned at the front end is displaced in the longitudinal direction by facially contacting a ramp  79  extending helically and acting radially. The longitudinal displacement towards the left causes the loosing of a catch  81 , which safely locks the hook  9  in the operational position. In order to suppress this function during the reverse rotation, i.e. when cutting threads, when the control disk  17  occupies the same position, the control rod  69  is diverted by the facial control  75  in the axial direction in reference to the control disk  17 , without influencing the position in the longitudinal direction. This way, the hook lock can only be loosened by a rotation of the control disk  17  in the positive direction.  
         [0036]     List of Reference Characters 
    1 Sewing machine     2 machine housing     3 primary shaft     7 lower arm     9 hook     11 transporter     13 upper drive     15 needle rod     17 control disk     19 socket     21 sprocket     23 1 st  facial surface     25 guide groove     27 control pin     29 horizontal guide     31 guide pin     33 carrier     35 slide bar     36 frontal end of  35      37 tooth segment     39 cutting device     40 rear end of  39      41 cutting edge     42 frontal end of  39      43 thread hook     44 thread exiting opening at  43      45 control curve     47 sensor finger     48 rear end of  49      49 lifting rod     50 frontal end of  49      51 threaded screw     53 threaded screw     55 oblong holes     57 oblong holes     59 lowering element     60 tensile spring     61 drive sprocket     63 drive motor     65 2 nd  facial surface     67 radial control path     69 control rod     70 rear end of  69      71 1 st  hook     72 sensor head     73 control surface     74 2 nd  hook     75 facial control path     77 locking lever     79 ramp     81 catch     83 rotational knob     85 fork     87 curved disk     89 sensor finger     135 curve     149 curve     169 curve