Abstract:
A connecting unit for loose ends of a traction device includes a body having a traction device passage to receive the ends of the traction device and a clamping device positioned in the traction device passage. The traction device passage has a first opening into which the ends of the traction device can be inserted. The clamping device is adapted to receive the ends of the traction device and has an adjustment mechanism which biases the clamping device in a direction of a wall of the traction device passage.

Description:
RELATED APPLICATIONS 
   This is a continuation application of co-pending international patent application PCT/EP2006/007586 (WO 2007/014746 A1) which claims priority of the German patent application DE 10 2005 038 446.3, filed on Aug. 3, 2005, which is fully incorporated by reference herewith. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a connecting unit for loose ends of traction device. 
   RELATED PRIOR ART 
   In the field of order-picking technique conveyor lines, such as roller conveyors, are typically driven by one or more motors. For this purpose the motors are connected to elements of the conveyor line to be driven via traction device. As a rule, form-closed traction device, particularly toothed belts and chains are used as traction device. Recently, toothed belts have prevailed due to maintenance reasons. A toothed belt can have the shape of an endless belt, and, for example, can be guided around two deflection pulleys being belt sprockets. The deflection pulleys are arranged at the ends of the conveyor line. One of the deflection pulleys can be driven by the motor. The other pulley runs idle or is also driven by the toothed belt. 
   Endless belts are made from manufacturers either in the form of a ring so that connecting loose belt ends is not necessary, or as yard goods. If yard ware is used the loose ends have to be connected with each other. For this purpose it is known in the prior art to weld the ends to each other, particularly if the yard ware is made of plastic. However, problems arise since welded connections can only transmit 40 to 50% of the force which can be transmitted by belts actually being formed annularly. Common drive belts have a traction carrier consisting, for example, of steel ropes and plastic cores. However, those are interrupted at welding seam locations. 
   Another problem exists in that belts, which are actually annular, are only available up to lengths of 24 meters at maximum. 
   Another option for connecting loose belt ends to each other consists of using a fastener. Such fasteners are disclosed in the documents DE 195 34 932 A1 and DE 297 05 941 U1. 
   The fastener typically is an articulated element having two toothed sections into which the ends of the toothed belt can be put. After placing respective counterparts therein the toothed sections are squeezed with the toothed belts. 
   This type of toothed belt fastener is irreversible. The squeezed part of the toothed belt cannot be released from the fastener any more. Since an end section of the toothed belt extending over several belts is squeezed, it is no longer possible, after releasing the fastener, to re-close the toothed belt, thus the entire toothed belt becomes useless. 
   A particular problem is to be seen in that such fasteners occasionally extend in all directions, i.e. fastener elements can be provided in the front, laterally as well as in the back. Then, guiding the fastener around return pulleys is not possible. 
   SUMMARY OF THE INVENTION 
   Therefore, it is an object of the present invention to provide an enhanced connecting unit. The connecting unit should be usable particularly for toothed belts, be guidable around return pulleys as well as transmit drive forces by 100%. Further it is desirable that belts, or also single parts of the belt, can be easily replaced. 
   This object is achieved by a connection unit for loose ends of a traction device, wherein the connecting unit includes a body having a traction device passage for receiving the ends of the traction device, and a clamping device adapted to receive the ends of the traction device and being arranged within the traction device passage, wherein the traction device passage has a first opening into which the ends of the traction device are insertable, and wherein the clamping device has an adjusting mechanism, operation of which urges the clamping device in the direction of a wall of the traction device passage. 
   By inserting the ends of the traction device to be connected to each other in one and the same opening, the connection unit according to the present invention merely extends at one side of the traction device. Deflection around deflection pulleys and drive pulleys thus is possible without any problem. Due to the short length of the connecting unit smaller pulley diameters can be used. 
   The clamping device does not squeeze the ends of the traction device but presses the same (reversibly) to the walls of the traction device passage and thus allows load bearing connection of loose ends of the traction device. 
   Additionally, drive force can be transmitted up to 100% by the connecting unit in accordance with to the invention. 
   According to a preferred embodiment the adjusting mechanism urges the clamping device in opposite directions against the wall of the traction device passage. 
   In this case, the traction device is laterally running along the clamping device so that the traction device, if the adjusting mechanism is actuated, respectively is clamped between the wall of the traction device passage and the clamping device. 
   Even further, it is preferred that the traction device passage has a second opening into which the clamping device can be inserted into the connecting unit from the outside, and that the wall connects the first and second openings to each other. 
   In this case, the traction device passage passes through the body of the connecting unit completely, the ends of the traction device can be easily inserted into the connecting unit, wherein the clamping device is subsequently inserted into the traction device passage, particularly from opposite direction, in order to clamp the loose ends of the traction device with the body of the connecting unit. 
   The body of the connecting unit preferably includes a ground plate and at least two jaw elements, wherein the traction device passage is formed between the jaw elements, and the jaw elements are arranged on the ground plate along a longitudinal axis of the ground plate. 
   In this manner the connecting unit in accordance with the present invention can be formed modularly. This facilitates manufacturing of the individual components as well as adaptation to different dimensions of the track device or the magnitude of forces to be transmitted. 
   Further, it is advantageous that a cover plate is additionally provided being arranged oppositely to the ground plate having the jaw elements. 
   The cover plate prevents the clamping device, in clamped state, to jump out of the traction device passage. 
   The edges of the first opening are, in accordance with another preferred embodiment, rounded in the direction of the traction device passage. 
   The rounding of the edges prevents the traction device from being loaded too heavily at a location where it enters the connecting unit which could lead to damage of the traction device. Thus, the lifetime of the traction device is increased. 
   Preferably, the traction device passage tapers wedge-shaped from the second opening in the direction of the interior of the body of the connecting unit. 
   The wedge shape facilitates the clamping of the loose ends of the traction device with the clamping device by moving the clamping device particularly away from the second opening, i.e. is inserted deeper into the traction device passage, so that the forces applied on the wall of the traction device passage are increased further. 
   According to another embodiment the clamping device includes a wedge-shaped element being formed such that its side faces, building an acute angle with respect to each other, clamp the ends of the traction device between each other and the wall, if the ends of the traction device are inserted into the first opening. 
   As already mentioned above, the wedge shape facilitates application of forces onto the wall of the traction device passage. 
   Additionally, it is advantageous that the clamping device includes a wedge-shaped element and a separate receiving element for each end of the traction device. 
   In this case, the clamping device is at least formed by three parts which increases the possibilities of how to connect the loose ends of the traction device to each other. 
   According to another preferred embodiment the clamping device additionally includes a locking bar, and the body of the connecting unit comprises in the region of the second opening additional recesses into which the locking bar is insertable such that the wedge-shaped element cannot escape from the traction device passage, if the wedge-shaped element is completely located within the traction device passage. 
   The locking bar represents an element effecting counter-force necessary for the clamping, so that the ends of the traction device cannot release by themselves. Further, the clamping device acts self-clamping. The more tensile stress is applied to the traction device, the stronger the clamping device is squeezed by being pulled in the direction of the first opening. 
   Additionally, it is advantageous that the adjusting mechanism includes at least one screw being guided through the passage within the locking bar such that the wedge-shaped element can be moved into the traction device passage. 
   This measure ensures that the force applied for clamping can be changed afterwards, particularly can be increased. 
   Another advantage has to be seen in that the adjusting mechanism includes another screw guided through a non-threaded passage within the locking bar and which can be screwed into a threaded bore of the wedge-shaped element. 
   This measure ensures that the clamping device can be also moved out of the traction device passage if the loose ends of the traction device have been clamped heavily with each other (in advance). 
   Preferably, the receiving element respectively comprises a first side for receiving one end of the traction device, and a second side arranged opposite to the first side and contacting the wedge-shaped element in inserted state. 
   The wedge-shaped element can also slide along the back of the receiving element, so that the strength by which the traction device is tightened, by moving the wedge-shaped element further down the traction device passage, can be varied in a simple manner. 
   According to another embodiment the receiving element has an L-shaped section, the shorter leg thereof extending externally from the second opening in an inserted state, wherein in the area of the shorter leg another adjusting mechanism, or particularly a radical screw, is provided. 
   By the aid of the other adjusting mechanism the force can be adjusted by which the traction device is tightened. 
   According to another embodiment the traction device has a profile at least at one side, particularly being formed as toothed belt. Preferably, the reception of the ends of the traction device happens form-closed. 
   It is to be understood that the above-mentioned and the following features to be explained can be used not only in the respectively indicated combination but also in other combinations or alone without departing from the scope of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention are depicted in the drawings and will be explained in more detail with reference to the following description, wherein: 
       FIG. 1  is a schematic top view of a connecting unit according to the present invention; 
       FIG. 2  is a schematic perspective view of the connecting unit of  FIG. 1 ; and 
       FIG. 3  is a sectional view through the connecting unit of  FIG. 2  in a squeezed state. 
   

   In the following description like elements are designated by like reference numerals. 
     FIG. 1  shows a top view of a connecting unit  10  in accordance with the present invention. 
   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The connecting unit  10  includes a body  12  and a clamping device  14 . 
   In  FIG. 1  the connecting unit  10  is depicted along its longitudinal axis  16 . The body  12  comprises two jaw elements  18  and  20  arranged at left hand side and right hand side of the center axis  16 , respectively. The jaw elements  18  and  20  are connected to a ground plate  22 . The ground plate  22  has an opening  24 , the function of which will be explained in more detail in the following. Additionally, cover plate  26  (not shown in  FIG. 1 ) can be provided, but is not shown in the illustration of  FIG. 1  for simplification purposes. This cover plate  26  also has an opening  28  (cf.  FIG. 2 ) arranged opposite to the opening  24  of the ground plate  22  in assembled state of the body  12 . 
   Both of the jaw elements  18  and  20  have, according to the embodiment shown in  FIG. 1 , a substantially L-shaped cross section. The short legs of the L-shaped cross section are rounded towards the center axis  16 . The roundings define first opening  30  into which loose ends of traction devices, for example of toothed belts, can be inserted for connection (cf. also  FIG. 3 ). The space between the two jaw elements  18 ,  20  along the longitudinal axis  16  defines traction device passage  32 . Within the traction device passage  32  the ends of the toothed belts (not shown) are squeezed by the clamping device  14  for connecting the loose ends of the toothed belt to each other in a form-closed manner. The jaw elements  18  opposite to the first opening  30 ,  20  define a second opening  34  into which the clamping device  14  can be inserted from the outside into the traction device passage  32 . 
   The clamping device  14  comprises a wedge  40 , two receiving elements  42 ,  44  as well as a locking bar  46 . 
   The wedge  40  has a recess  50  at its base side  48  being that broad that the locking bar  46  can be received. The other two sides  52  and  54  of the wedge  40  together form an acute angle, and here are formed smoothly. 
   The two receiving elements  42  and  44  here have an L-shaped cross section. Side  56  opposite to the wedge  40  preferably is formed smoothly, too. The advantage thereof is that the receiving elements  42  and  44 , if they are inserted in combination with the wedge  40  into the traction device passage  32  (cf. also  FIG. 3 ), can better slide along the faces  52  and  54  of the wedge  40 . Due to the relative movement of the wedge  40  against the receiving elements  42  and  44  the force can be increased by which the loose ends of the toothed belt can be connected to each other in a form-closed manner. The connection is described in more detail in the context of  FIG. 3 . 
   The receiving elements  42  and  44  comprise a negative toothing on side  58  opposite to side  56 , in order to allow form-closed reception of the toothed belts being not depicted in  FIG. 1 . The shape of the side  58  depends on the profile of the ends of the traction device to be connected to each other. 
   Further, the receiving elements  42  and  44  comprise threaded bores  60  within a region projecting over the jaw elements  18  and  20  from the traction device passage  32  in assembled state (cf.  FIG. 3 ). Due to the threaded bore  60  screws  62  can be screwed in. 
   The locking bar  46  also comprises at least one threaded bore  60 , for respectively receiving another screw  64 . 
   Further, the wedge  40  comprises in the region of the recess  50  a bore  51 , the function of which will be explained in greater detail below. 
   Referring to  FIG. 2  the connecting unit  10  of  FIG. 1  is depicted in a perspective view. 
   The cover plate, not depicted in  FIG. 1  for facilitating the illustration, is depicted in  FIG. 2  as being lifted from the jaw elements  18  and  20 . The connection between the cover plate  26  and the remaining body  12 , for example, can be achieved by using screws. However, the cover plate  26  can also be secured to the rest of the body  12  in a fixed manner by riveting, welding, etc. the cover plate  26  onto the jaw elements  18  and  20 . Further, the opening  28  within the cover plate  26  is shown. In assembled state of the body  12  the opening  28  is located opposite to the opening  24  of the ground plate  22 . 
   In  FIG. 2  the receiving element  42  is arranged within the traction device passage  32 . One can see that in a neck region of the receiving element  42  two adjusting screws  62  are provided, by the aid of which the insertion depth of the receiving element  42  into the traction device passage  32  can be varied. 
   Also, the locking bar  46  is depicted in  FIG. 2  in more detail. The locking bar  46  is provided with two lateral threaded bores  60  into which the screws  64  can be screwed in. By the aid of the screws  64  the penetration depth of the wedge  40  into the traction device passage  32  can be varied. Another screw  66  can be provided between the two lateral screws  64 , the screw  66  being insertable into (not shown) bore of the locking bar  46  not having any thread. The screw  66  can be screwed into the threaded bore  51  of the recess  50  within the wedge  40 . The wedge  40  can also be moved from the traction device passage  32  by the aid of the screw  46  after squeezing of the ends of the traction device has occurred. As a rule, the clamping device  14  is squeezed within the traction device passage  32  heavily so that manual release of the clamping device is not possible. 
   With reference to  FIG. 3  the connecting unit  10  is illustrated in a schematic elevational view, wherein the connecting unit  10  connects two ends  72  and  74  of a toothed belt  70  with each other by frictional connection. 
   For this purpose the toothed ends  72  and  74  have been inserted from the outside into the first opening  30 . The clamping device  14  are inserted into the traction device passage  32  through the second opening  34 . Therefore, first the receiving elements  42  and  44  are inserted and subsequently the wedge  40  is arranged between these receiving elements  42  and  44 . 
   In order to arrest the wedge  40  within the traction device passage  32  the locking bar  64  is inserted into the openings  24  and  28  (cf.  FIG. 2 ) from the outside. The length of the locking bar  46  preferably is selected such that the bar  46  flushes with the ground plate  22  and the cover plate  46  in the inserted state. The size of the openings  24  and  28  in the axial direction  16  is selected such that sufficient clearance is provided in order to insert the locking bar  46 . 
   Now, also the function of the recess  50  within the wedge  40  becomes clear. The recess  50  within the wedge  40  serves for receiving the locking bar  46 . The orientation of the wedge  40  relative to the axis  60  can be adjusted by the screws  64 . The deeper the screws  64  are screwed in, the “deeper” the wedge will be urged into the traction device passage  32 . The recess  50 , therefore, preferably is formed such that the bottom of the recess  50  forms a stop for the screws  64 . A threaded bore  51  is merely provided for the screw  66  (cf.  FIG. 2 ) in the bottom of the recess  50 . By screwing in the screw  64  the wedge  40 , in the squeezed state, can be screwed out of the traction device passage  32 . 
   The screw  62  provided at the receiving elements  42  and  44  in the region of the second opening  34  serves to adjust the penetration depth of the receiving elements  42  and  44  in the traction device passage  32 . The jaw elements  18  and  20  serve as stops. The screws  62  of the receiving means  42  and  44  are shown in  FIG. 3  in a state in which the jaw elements  18  and  20  do not contact the same. However, the screw  62  could be screwed in into the direction of the jaw elements  18  and  20  for urging, in turn, the receiving elements  42  and  44  in the direction of the second opening  34 , i.e. out of the traction device passage  32 . In this manner, the toothed belt  70  can be stretched arbitrarily. 
   Since both ends  72  and  74  of the toothed belt  70  are inserted at the same side of the connecting unit  10 , i.e. through the first opening  30 , into the connecting unit  10 , no elements are arranged at the side  76  of the toothed belt  70  having the profile. Consequently, it is possible to guide a toothed belt  70  connected with the connecting unit  10  around a deflection pulley  78  indicated by phantom lines in  FIG. 3 . 
   Generally, it is to be noted that the connecting unit  10  of the invention is very flat, preferably has the size of the width of the toothed belt  70 . 
   According to another embodiment the clamping device  14  can also be assembled of less elements. The receiving elements  42  and  44  could be omitted, wherein the faces  52  and  54  of the wedge  40  should be provided with a negative profile if a toothed belt  70  having a profile is to be squeezed. 
   Alternatively, the wedge  40  could be mounted axially movable within the traction device passage  32  such that it does not have to be inserted from the outside through the second opening  34  into the traction device passage  32 . In this case, one has to take care only of providing a suitable adjusting mechanism by which the axial position of the wedge  40  can be adjusted. 
   It is to be noted that the number of different adjusting screws can be chosen arbitrarily. With the depicted embodiments respectively only two adjusting screws are provided for ensuring redundancy required for safety reasons. It is also clear that other adjusting mechanisms could be used instead of screws (e.g. click-stop fasteners or the like). 
   Also the shape of the jaw elements  18  and  20  can be varied. With the embodiment described here the jaw elements  18  and  20  are formed round in the region of the first opening  30 . However, other shapes are possible. L-shape is not necessarily required. 
   The shape of the traction device passage  32  can be varied. In  FIGS. 1 to 3  the traction device passage  32  is always depicted with a base area having a triangular shape. However, the traction device passage  32  could alternatively have a base area of rectangular shape. In this case, the wedge  40  were to be replaced by an ashla-shaped element onto which the adjusting mechanism effects a separating movement on the sides opposite to the jaw elements  18  and  20 .