Abstract:
In the top transport device of a sewing machine, the top transport foot ( 15 ) moves in a vertical slot ( 27 ) in the arm ( 17 ), with which the top transport foot ( 15 ) is driven. This arrangement enables the top transport foot ( 15 ) to be displaced upwards into the rest position, so that accessories can be fixed to the presser bar ( 11 ).

Description:
BACKGROUND 
   The invention is directed to a top transport device for sewing machines, in particular, with a presser bar and presser foot arrangement. 
   Top transport devices on sewing machines are known. They are used to also transport the sewing material from the top side in the sewing direction in sync with the feed dog arranged under the sewing material in the lower arm and therefore to guarantee that there is no mutual shift between the material on the top and the material on the bottom. 
   A known device is described in DE-C1 3435633. This device comprises, in addition to the spring-loaded presser bar, which is mounted for vertical movement on the sewing machine and to which the presser foot is fixed on the bottom, a top transport foot, which is driven by an arm in active connection with the drive of the sewing machine. If the top transport foot is to be activated, then it is connected by the sewer to the bottom end of the arm, i.e., suspended on the bottom end and held there by a spring pulling back the top transport foot. Here, the bottom arm end engages the shaft of the top transport foot. In contrast, if the top transport foot is not needed, then it can be disconnected from the arm and then slides upwards, pulled by the spring, until the foot end contacts the bottom end of the arm. The bottom of the top transport foot then always lies at a distance of about 15 mm from the needle plate and no longer influences the sewing process. However, the distance of the top transport foot bottom is small, such that no known accessories can be fixed to the presser bar. In addition, handling by the sewer in the area of the presser foot is obstructed by the top transport foot. 
   SUMMARY 
   One objective of the present invention is to create a top transport device, which can be moved upwards when not needed such that conventional accessories can be fixed to the presser bar and optimal handling of the sewing material is possible when the top transport is not needed. 
   Another objective of the present invention is to form the top transport such that it can be adjusted relative to the presser foot and the needle plate without disassembling the housing part. 
   These are met by a top transport device according to the invention. Advantageous configurations of the device are described in the dependent claims. 
   By dividing the arm, at least partially, into two parallel, spaced arm sections that guide the shaft of the top transport foot laterally, the top transport foot can be drawn upwards to a much greater extent and thus the area above the needle plate can be kept open for the installation of special devices. 
   Another advantage of the invention in one preferred embodiment is that no parts on the machine housing have to be removed for setting the top transport foot in the sewing direction and in the vertical direction. There is the further possibility of exchanging a top transport foot similar to the presser foot and replacing it with a foot that is adapted to the sewing material to be processed. In another advantageous configuration, only the foot bottom on the top transport foot can be exchanged in order to adapt its structure to the sewing material to be processed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is explained in more detail with reference to an illustrated preferred embodiment. In the drawings: 
       FIG. 1  is a front view of a sewing machine from the operator side; 
       FIG. 2  is a view of the sewing machine from the direction of the arrow P in  FIG. 1  with a schematic top transport device; 
       FIG. 3  is an enlarged representation of the presser bar, the presser foot, and also the top transport device, top transport foot in raised position; 
       FIG. 4  is an enlarged representation of the presser bar, the presser foot, and also the top transport device, top transport foot in lowered position, directly at the beginning of the transport of the sewing material; 
       FIG. 5  is an enlarged representation of the presser bar, the presser foot, and also the top transport device (partially cut away), with the top transport foot in a lowered position, directly at the end of the transport of the sewing material; 
       FIG. 6  is a view of the top transport device and the presser foot from the direction of the arrow H in  FIG. 2  (top transport in working position); 
       FIG. 7  is a view of the top transport device and the presser foot from the direction of the arrow H in  FIG. 2  (top transport in rest position); 
       FIG. 8  is a perspective view of the top transport device with exchangeable top transport foot and adjustment device; 
       FIG. 9  is a perspective representation of the arm, which carries the top transport foot; 
       FIG. 10  is a cross section through the height adjustment device for the top transport foot; 
       FIG. 11  is a longitudinal section through a first embodiment of an exchangeable top transport foot; 
       FIG. 12  is a longitudinal section through a second embodiment of an exchangeable top transport foot; 
       FIG. 13  is a perspective representation of a replacement bottom for a top transport foot; and 
       FIG. 14  is a perspective representation of the replacement bottom fixed on the top transport foot. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In  FIG. 1 , a household sewing machine with the reference symbol  1  can be seen shown schematically with a free arm  3 , an upper arm  5 , and a base plate  7 , on which the housing part  9  carrying the upper arm  5  and the free arm  3  is arranged. Furthermore, a presser bar  11  and a presser foot  13  attached to this presser bar can be seen. In the front view according to  FIG. 2 , behind the presser bar  11 , a top transport foot  15  and a driving arm, designated as arm  17  below, activating the top transport foot  15 , can be seen. In addition, a needle  19  and the needle rod  21  are shown above the presser foot  13 . 
   In  FIGS. 3 to 7 , which present the parts essential to the invention at an enlarged scale, in addition to the top transport foot  15  and the arm  17 , the driving means for the arm  17  are also shown but not described in more detail. The driving means move the arm  17 , when this is lowered, in sync with the feed dog (not shown). The kinematics of the driving gear, which include a plurality of levers and cams are not described here in more detail, because they can correspond, for example, to those from the state of the art. Obviously, other driving systems for the movement of the arm  17  are also possible. 
   The two primary elements of the top transport according to the invention are the configuration of the top transport foot  15  and the arm  17 . The arm  17  comprises two spaced, parallel arm sections  17   a  and  17   b , which are held connected to each other and form in-between a guidance space. The top and bottom end of the arm  17  can be held together by connecting members  23  and  24  ( FIG. 9 ). In addition, the top ends of the two arm sections  17   a ,  17   b  are coupled to the driving kinematics by a bolt  25 , which penetrates the bore holes  26  in the arm sections  17   a ,  17   b  (see  FIG. 3 ). In addition, a longitudinal guidance slot  27  is formed in each of the two arm sections  17   a ,  17   b . These two guidance slots  27  are used for guiding the top transport foot  15 , at whose top end a guidance bolt  28  engaging in the guidance slot  27  is inserted ( FIG. 4 ). 
   The top transport foot  15  is guided laterally with slight play in the guidance space between the inner sides of the two arm sections  17   a ,  17   b . In the raised position ( FIG. 3 ), the top transport foot  15  lies with its top end and also with its bottom end close to the top transport foot bottom  29  between the two arm sections  17   a ,  17   b.    
   The top transport foot  15  has the shape of a two-armed lever, with the connecting point  14  (knee) of the two lever sections  16   a ,  16   b  coming to lie outside of the two arm sections  17   a ,  17   b  in the raised position. The top transport foot  15  is then guided laterally in the region of its upper lever section  16   b  with the guidance bolt  28  in the guidance slots  27  on the arm  17 , and in the region of its lower lever section  16   a  in the guidance space of the arm  17 . The connecting point  14 , i.e., the knee, projects backwards from the guidance space. The two ends of the bolt  28  at the end of the upper lever section  16   b  of the top transport foot  15  contact the upper end of the slot  27  in the rest position. In this rest position, the top transport foot  15  is held by a spring  31 , which is suspended on one side on the connecting member  23  between the brackets  33  on the arm  17  and is held on the other side on the top transport foot  15  (holding point cannot be seen). In order to impart a defined position to the top transport foot  15 , at least one guidance cam  35  is formed on this top transport foot. This cam—when the top transport foot  15  is not in the working position—slides on the rear edges of the two arm sections  17   a ,  17   b . Consequently, the tip of the top transport foot bottom  29  is located in the rest position at the height of the bottom end  20  of the arm  17  and approximately at the height of a connecting point between the presser foot  13  and the presser bar  11  (see  FIG. 3 ). 
   In the working position ( FIG. 4 ), the top transport foot  15  is pulled or pushed downwards against the force of the spring  31  on the cam  37  by hand, guided upwards with the bolt  28  in the guidance slots  27 , and guided laterally between the arm sections  17   a ,  17   b . In this way, the top transport foot  15  pivots in the direction against the presser foot  13  and engages in the recess  18  formed there ( FIG. 8 ). When the top transport foot  15  is guided downwards, at least the guidance cam  35  slides on the upper leg of the top transport foot  15  under the bottom end  20  of the arm  17  (shown in  FIGS. 5 &amp; 8 ) and locks there. In this position, the top transport foot  15  is in active connection with a positive fit with the arm  17  and can be driven by this arm and the rods engaging the arm at the top. The tensile force of the spring  31  maintains the connection. The position of the top transport foot  15  shown in  FIG. 4  relative to the presser foot  13  is also maintained when the presser foot is lowered onto the sewing material, because the arm  17  and its drive follow the vertical movement in sync when the presser bar  11  is lowered. 
   From the perspective representation in  FIG. 8  and in  FIG. 10 , which present a preferred refinement of the invention, adjustment devices for adjusting the top transport foot  15  relative to the presser foot  13  are shown. The top transport foot  15  is adjusted in the vertical direction by a cam plate  44 , which is mounted on a threading-free section of a threaded bolt  39  so that it can rotate, and can be secured by a nut  41  (see  FIG. 10 ). The other end of the threaded bolt  39  is connected rigidly to an extension arm  43  projecting from the arm  17 . By rotating the cam plate  44  on the threaded bolt  39 , the vertical position of the arm  17  is defined and thus also the vertical position of the top transport foot  15  fixed to the arm. 
   The top transport foot is adjusted in the horizontal direction by two locking screws  45 , which engage in a slot  48  formed in an attachment lever  47  coupled to the sewing machine housing. For better clarity, in  FIG. 8  the locking screw  45  of the front attachment lever  47  is not shown or has been left out in order to make the slot  48  visible. The attachment lever  47  is connected to a rocker arm  51  in an articulated way with a connecting member  49 . By loosening the locking screws  45  and moving the attachment brackets  47  in the slot, the arm  17  is pushed horizontally by the connecting member  49 , which is coupled to the attachment lever  47 . 
   The top section  16   b  of the top transport foot  15  is guided by the guidance bolt  28  in the slots  27  of the arm  17 . This connection can be released by suitable means in the first embodiment according to  FIG. 11  and thus the top transport foot  15  can be removed from the arm  17  and replaced by a foot with a differently shaped bottom  53 . Before the top transport foot  15  is removed, the connection between the spring  31  and the top transport foot  15  must be loosened. The top transport foot  15  is loosened from the arm  17 , in that the hook-shaped top end  30 , which is locked on the guidance bolt  28 , is loosened from this bolt (hook-shaped end  30  visible in  FIG. 11 ). 
   In the second embodiment according to  FIG. 12 , the lower leg  16   a  of the top transport foot  15  is formed so that it can be released from the upper leg  16   b . The top end of the lower leg  16   a  engages in a slot  32  in the connecting point  14  to the upper leg  16   b  and can be fixed with a suitable latching element  34 . A tension screw or the like can be used as the latching element  34 . 
   In the third embodiment according to  FIGS. 13 and 14 , only the bottom  53  on the lower leg  16   a  is removed for changing the properties of the top transport foot  15 . The connection between the bottom  53  and the lower end  55  of the lower leg  16   a  can be realized, for example, by a close sliding fit, a dovetail joint, or the like. 
   The replacement of the top transport foot  15  by another foot with a differently shaped bottom  53  is used to adapt the top transport foot  15  to the sewing material to be processed or to the surface properties of this material. Very fine materials, such as silk, require differently shaped top transport foot bottoms  53  than materials with a very rough structure. 
   
     
       
             
           
             
             
           
         
             
                 
             
             
               Legend 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               1 
               Household sewing machine 
             
             
               3 
               Free arm 
             
             
               5 
               Upper arm 
             
             
               7 
               Base plate 
             
             
               9 
               Housing part 
             
             
               11 
               Presser bar 
             
             
               13 
               Presser foot 
             
             
               14 
               Connecting point of 15a/16b 
             
             
               15 
               Top transport foot 
             
             
               16 
               Shank of 15 
             
             
               17 
               Arm 
             
             
               18 
               Recess in 13 
             
             
               19 
               Needle 
             
             
               20 
               Lower end of 17 
             
             
               21 
               Needle bar 
             
             
               23 
               Connecting element (top) 
             
             
               24 
               Connecting element (bottom) 
             
             
               25 
               Bolt 
             
             
                 
               (transfers advance to 17) 
             
             
               26 
               Bore holes for 25 
             
             
               27 
               Slot 
             
             
               28 
               Guidance bolts, engaging in slots 
             
             
               29 
               Transport base 
             
             
               30 
               Top hook-shaped end 
             
             
               31 
               Spring 
             
             
               32 
               Slot 
             
             
               33 
               Bracket 
             
             
               34 
               Latching means 
             
             
               35 
               Guidance cams 
             
             
               37 
               Cams 
             
             
               39 
               Threaded bolt 
             
             
               41 
               Nut 
             
             
               43 
               Extension arm 
             
             
               44 
               Cam plate 
             
             
               45 
               Clamping screw 
             
             
               47 
               Attachment lever 
             
             
               48 
               Slot 
             
             
               49 
               Connecting element 
             
             
               51 
               Rocker arm 
             
             
               53 
               Base of 15 
             
             
               55 
               Lower end of 16a