Abstract:
A fastening element feeding device for a power drive-in tool includes a transportation device ( 30 ) having a transportation wheel ( 32 ) for a magazine strip ( 50 ), at least one actuation member ( 35 ) displaceable in a control track ( 16 ) in a first component ( 11 ) for effecting a relative displacement between the first component ( 11 ) and the second component ( 21 ), which results in a transportation displacement of the transportation wheel ( 32 ); a displacing member ( 31 ) having one end region ( 39 ) which is adjacent to the head ( 22 ), supporting the rotary axle (D) together with the transportation wheel ( 32 ), and having another of its end regions ( 38 ) supporting the at least one actuation member ( 35 ); and a guide arrangement that provides for displacement of the displacing member ( 31 ) over the second component ( 21 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fastening element feeding device for a power drive-in tool and which includes a first component connectable with the power drive-in tool and a second component displaceably supported on the first component and having a head applicable against a constructional component, and a transportation device for feeding fastening elements arranged in a magazine strip in a drive-in channel. The transportation device includes a transportation wheel for the magazine strip and rotatably supported on a rotary axle, at least one actuation member displaceable in a control track in a first component for effecting a relative displacement between the first component and the second component which results in a transportation displacement of the transportation wheel. 
     2. Description of the Prior Art 
     Fastening element feeding devices for power drive-in tools such as, e.g., screwdriving power tools have a head that is placed on a constructional component and serves for guiding fastening elements such as, e.g., screws before and during a setting process. The head can be formed, e.g., as a part of a magazine with fastening elements or of a fastening element transportation device that is mountable on a flange of a drive-in tool. 
     German Utility Model DE 203 09 492 U1 discloses a screwdriving power tool with a screw feeding device having a first component in form of a holder that is mounted on a flange of the tool housing. A second component of the screwdriving tool in form of a screw guide is arranged on the first component with a possibility of displacement relative thereto, with the end of the screw guide, which faces in the operational direction, being placeable against a constructional component. On the second component, there is provided a rotatable disc on which a pawl is arranged. The pawl has an arm that projects from the rotatable disc and has a fixation pin on its end remote from the disc. The fixation pin extends through curved opening in a drive block and extends through a guideway in the holder. When the screw guide is displaced, upon the screwdriving tool being pressed against a constructional component, into the holder, the fixation pin is displaced along the guideway, with the pawl being rotated by the arcuate curved opening in the drive block. Thereby, the screws are fed through the screw guide and toward the screwdriving working tool. 
     The drawback of the above-described feeding device consists in the arrangement of the curve guide that curves with respect to the rotating disc and extends substantially transverse to the operational axis which is defined by the screwdriving working tool, which unfavorably influences the kinematics of the transport mechanism and leads to jamming and soiling of the curved guide. In addition, for starting the press-on process, a high press-on force, which is applied by the user, is needed for transportation of the screws. 
     German Publication DE 25 41 046 A1 discloses a power tool for screwing screws in, in which a slide is displaceably supported in the tool housing. In the slide, there is arranged a device for a stepwise transportation of screws in a screw-in position. The transportation device includes a ratchet wheel with two ratchet discs and a clutch disc. The clutch disc has projections that engage in corresponding recesses in the ratchet disc and are retained there by a biasing force. On the clutch disc, there is further provided a pin displaceable in a guide slot in the tool housing and in a slot in the slide. Upon the front end of the slide being pressed against a workpiece, the pin and the clutch disc connected therewith are rotated in the clockwise direction as a result of the positive guidance. This causes displacement of the strip with screws and feeding of a screw to the screw-in position. Upon lifting of the slide off the constructional component, the pin is displaced in the opposite direction, with a pawl preventing rotation of the ratchet discs in the counterclockwise direction. As a result, the clutch disc with the projections disengages from the ratchet disc against a spring biasing force and displaces alone in the counterclockwise direction to its initial position. 
     The drawback here, as in the German Utility Model DE 203 09 492 U1, consists in that for starting the press-on process, a high press-on force, which is applied by the user, is needed for transportation of the screws. Also, the transportation mechanism is susceptible to soiling and the resulting therefrom, failures. 
     German Patent DE 42 19 095 C1 discloses a displacement device with a ratchet wheel for a drive-in tool in which the ratchet wheel is supported on an end of a first arm of a two-arm pivotal lever, with the control pin being supported on the second arm. The two-arm pivotal lever in supported on a drag bearing arranged between the first and second arms. Upon a stop of the slide being pressed against a workpiece, the pivotal lever pivots, as a result of a positive guidance, in the clockwise direction, together with the ratchet wheel. The ratchet wheel is stopped by a stop catch and does not pivot further but still transports further screw strip. Upon the drive-in tool being lifted off the workpiece, the slide is pushed out of the housing by a spring, and the positively guided pin pivots the pivotal lever in the counterclockwise direction, with the rungs of the ratchet wheel still engaging in rim recesses of the screw strip. 
     The drawback of the displacement device of the German Patent consists in that the pivotal lever is very sensitive to soiling which can adversely affect its function. 
     Accordingly an object of the present invention is to provide a fastening element feeding device for a power drive-in tool in which the drawbacks of the known feeding devices are eliminated. 
     Another object of the present invention is a fastening element feeding device for a power drive-in tool and which has a simplified construction and provides for a reliable transportation of the screw strip. 
     SUMMARY OF THE INVENTION 
     These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a fastening element feeding device of the type described above in which the transportation device has a displacing member having one of its end regions, which is adjacent to the head, supporting the rotary axle together with the transportation wheel and having its another end region supporting the at least one actuation member, and has a guide means providing for displacement of the displacing member over the second component. Advantageously, the displacing member is displaced along a curved track. Upon the drive-in tool being pressed against a constructional component, the transportation wheel, together with the displacing member, is displaced in the transportation direction of the strip, whereby because of guidance of the displacing member, no danger of jamming, as a result of soiling, exists even during displacement to the initial position. These measures also permitted to obtain a technically simple, easily manufacturable and reliably operating transportation mechanism. 
     Advantageously, the guide means has at least one first guide curve and at least one second guide curve both provided on the second component and first and second control pins displaceable along the first and second guide curves respectively. The first and second guide curve are spaced from each other in a direction of an operational axis defined by the drive-in channel and have each a first end adjacent to the operational axis and a second end remote from the operational axis. These measures provide separate guides for the front and rear ends of the displacing member. The virtual rotational axes, which the guide curves produce and which are relevant for the transportation of the fastening elements, are located outside of the housing, with their position changing, whereby the press-on force necessary for the transportation of the strip in accordance with the press-on path, is optimized. In addition, the displacement path can be optimally adapted to the transportation of the strip. 
     It is further advantageous, when the first control pin is formed coaxially with the actuation member and the second control pin lies concentrically with the rotary axle of the transportation wheel. This insures a compact construction. The first control pin is located in the initial position of the transportation device, preferably, at the first end of the first guide curve, which is located adjacent to the operational axis, whereas the second control pin is located in the initial position at the end of the second guide curve, which is remote from the operational axis. This insures a definite position of the displacing member. Advantageously, the first guide curve has a curvature that curves away from the operational axis between its adjacent and remote ends and the second guide curve has a curvature that curves toward the operational axis between its remote and adjacent ends. Thereby the front end of the displacing member, adjacent to the head performs a different curved movement than the rear end of the displacing member. This increases the resistance of the transportation device to tilting during a return movement. 
     Advantageously, the transportation wheel has two, spaced from each other along the rotary axle, ratchet discs, and the device further comprises two ratchet mechanisms associated with respective ratchet discs which provide for a separate control of the two ratchet discs. 
     Advantageously, there is provided return means associated with the first ratchet disc. The first ratchet mechanism is located between the return means and the first ratchet disc, the device further includes control means for controlling the return means so that rolling of the transportation wheel over the magazine strip is possible only in a return direction of the transportation device. Thereby, an additional locking device for stopping the magazine strip is not any more necessary, which permits to reduce costs. The magazine strip, thus, is reliably held by the transportation wheel at each point in time. According to a constructively simple solution, the control means includes at least one control curve provided on the second component and at least one control member arranged on a control plate and displaceable over the control curve. The first ratchet mechanism includes spring means secured on the control plate. 
     The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings show: 
         FIG. 1  a side view of a fastening element feeding device according to the present invention and which is mounted on a drive-in tool; 
         FIG. 2  an exploded view of a detail of the fastening element feeding device shown in  FIG. 1 ; 
         FIG. 3  an exploded view of a further detail of the fastening element feeding device shown in  FIG. 1 ; 
         FIG. 4  a cross-sectional view of the fastening element feeding device shown in  FIG. 1  in an initial position thereof; 
         FIG. 5  a cross-sectional view of the fastening element feeding device shown in  FIG. 2  in a position in which the drive-in tool is partially pressed against a constructional component; and 
         FIG. 6  a cross-sectional view of the fastening element feeding device shown in  FIG. 2  in a position in which the drive-in tool is completely pressed against the constructional component. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1-6  show a fastening element feeding device according to the present invention which is generally designated with a reference numeral  10  and is releasably mounted with a coupling section  14  on a flange  81  of a hand-held power drive-in tool  80  shown only schematically, with dash lines, in  FIG. 1 . The drive-in tool  80  is formed here as an electrically driven screwdriving tool. 
     The fastening element feeding device  10  is formed as a screw-containing magazine with an integrated transportation device  30  for transporting a magazine strip  50 . In the fastening element feeding device  10 , a drive-in working tool  15 , which is formed as a screwdriving working tool, is displaceable in a drive-in channel  12  and is rotationally driven by the power drive-in tool  80 . With the transportation device  30 , in a single step, upon the tool  80  being pressed with the fastening element feeding device  10  against a constructional component U, a fastening element  51  is displaced into the drive-in channel  12  in front of the drive-in working and tool  15  to be subsequently driven in the constructional component U with the drive-in tool  15 . The drive-in channel  12  defines an operational axis A of the fastening element feeding device  10 . 
     The fastening element feeding device  10  includes a first component  11  that contains the coupling section  14  and is formed as a guide housing, and a second component  21  displaceably supported on the first component  11 . The second component  21  is supported against the first component  11  by an elastic return member  17 . The second component  21  is formed as a slide and has two guide sections  23  which are axially displaceable in guides  13  provided on the first component  11 . The second component  21  carries the transportation device  30  and displaces the magazine strip  50  with fastening elements  51  in a strip guide  20 . The second component  21  has a head  22  which can abut the constructional component U with its end surface  24 . The head  22  is spaced from a support  29  having two side support members  25  between which a displacing member  31  of the transportation device  10  is displaceably supported, as particularly shown in  FIG. 3 . The distance between the head  22  and the support  29  is adjusted by a mechanism, not shown in the drawings, in order to be able to use fastening elements having different lengths. 
     As particularly shown in  FIGS. 2 through 6 , the displacing member  31  of the transportation device  30  has a curved or bent profile and carries, at its first end or end region  38  adjacent to the coupling section  14 , two first control pins  36 . The first control pins  36  are displaceably arranged in a receptacle  47  in which they are supported against each other by a spring  42 . The first control pins  36  extend through respective first guide curves  26  along which they are displaced. The control pins  36  forms, at their ends remote from the receptacle  47 , respective actuation members  35  extending into respective guide curves  16  in the first component  11  and displaceable therein. 
     At a second end region  39  or an end opposite the first end region  38  of the displacing member  31 , a transportation wheel  32  is rotatably supported on a rotary axle D displaceable in a bearing bush  49 . At both opposite ends of the rotary axle D, there are formed second control pins  37  displaceable in respective guide curves  27  of the support  29  on the second component  21 . 
     The first guide curve  26  has a curvature that bends away from the operational axis between an end  61  adjacent to the operational axis A and remote from the head  22  and an end  62  remote from the operational axis A and adjacent to the head  22 . The second guide curve  27  has a curvature that curves toward the operational axis A between an end  71  remote from the operational axis A and from the head  22  and an end  72  adjacent to the operational axis A and the head  22 . The curvatures of both first and second guide curves  26  and  27  are shown in  FIGS. 2 ,  4 ,  5  and  6 . The specific arrangement of the first and second guide curves  26  and  27  prevents tilting of the displacing member  31  that is guided by the control pins  36  and  37  along the guide curves  26 ,  27 . 
     The transportation wheel  32  has first and second ratchet discs  33  and  34  and a return member  40  that cooperates with the first ratchet disc  33 . A ratchet mechanism  43 ,  44  is associated with a respective one of the ratchet discs  33 ,  34 . The ratchet mechanism  43 ,  44  each has a spring  45 ,  46 . The step-forming rungs  53 , which are formed on the ratchet discs  33 ,  34 , engage in transportation openings provided in the magazine strip  50  that is located in the strip guide  20  in the second component  21 . 
     The return member  40  has a control plate  41  on which a control member  48  in form of a pin is formed. The control member  48  engages in a control curve  28  of a support member  25  of the support  29  of the second component  21  ( FIGS. 2 through 6 ). 
     In the initial position of the fastening element feeding device  10 , which is shown in  FIGS. 1-4 , the second component  21  is spaced from the first component  11  to a most possible extent by the biasing force of the return member  17  which is formed, e.g., as a spiral spring. The first control pins  36  are located at the first ends  61  of the first guide curves  26 , and the second control pins  37  are located at the first ends  71  of the second guide curves  27 . The transportation wheel  32  engages with its rungs  53  in the transportation openings in the magazine strip  50  in the strip guide  20 . 
     With the drive-in tool  40  being pressed with the arranged thereon, fastening element feeding device against a constructional component U, as shown in  FIG. 5 , the second component  21  is displaced inward into the first component  11  in direction of arrow  32 . As a result of this movement, the actuation members  35  are displaced in the first sections  18  of the control tracks  16  in a direction away from the operational axis A. 
     Thereby, the control pins  36 , which are associated with the control members  35 , are displaced in the direction of arrow  83  toward the second ends  62  of the first control curves  26 , and the rear first end region  38  of the displacing member  31  is displaced away form the operational axis A. The front second region  39  of the displacing member  31  is controlled separately by the control pins  37  engaging in the second guide grooves  27  and is displaced by the control pins  37  in the direction of the arrow  84  and toward the operational axis A, with the second control pins  37  movable toward the second ends  72  of the second guide curves  27 . The transportation wheel  32  with both ratchet discs  33 ,  34  would also move, as a result of the displacement of the displacing member  31 , in the direction of the arrow  84  toward the operational axis A. The second ratchet disc  34  is stopped by the second ratchet mechanism  44  and its spring  46 , so that the magazine strip  50  is displaced by then non-rotatable transportation wheel  32  in the direction of arrow  52 . 
     In  FIG. 6 , the magazine strip  50  has been transported by the transportation device  30  by a whole step, with a fastening element  51  being displaced in drive-in channel  12  for being driven with the drive-in working tool  15  in the constructional component U. The displacing member  31  would be displaced with the transportation wheel  32  in the above-described manner until the first and second control pins  36 ,  37  reach the second ends  62 ,  72  of the control curves  26 ,  27 . The actuation members  35  are displaced further, after the displacing member  31  reached its end position, in the second sections  19  of the control curves  16  that extend in the direction of the operational axis A. 
     After the drive-in or screw-in process has ended, upon lifting of the drive-in tool  80  and the fastening element feeding device  10  off the constructional component U, the second component  21  is pushed out of the first component  11  under action of the biasing force of the return member  17 . Thereby, the actuation members  35  are displaced along the second sections  19  of the control curves  16 . As soon as actuation members  35  are displaced in the first sections  18  of the control curves  16 , the first and second control pins  36 ,  37  are displaced in the first and second guide curves  26 ,  27  in the direction opposite the direction of arrows  83 ,  84  from the second ends  62 ,  72  of the first and second guide curves  26 ,  27  toward the first ends  61 ,  71 . The displacing member  31 , together with the transportation wheel  32 , is displaced thereby in the corresponding directions. During this return movement, the transportation wheel  32  rolls over the magazine strip  50 . The rolling over is controlled by the control member  40 , the control member  48  of which is displaced in the control curve  28 . The control plate  41  of the control member  40  is stopped upon the return movement of the displacing member  31  by the ratchet mechanism  43  and its spring  45 , on the first ratchet disc  33 . The second ratchet disc  34  continues to rotate and overrattles a position. The transportation device  30  and the fastening element feeding device  10  are again in the initial position with the active rolling-over of the transportation wheel  32  along the magazine strip  50 , the fastening element feeding device  10  need not be fixed in its position additionally by a locking device. 
     Though the present invention was shown and described with references to the preferred embodiment, such is merely illustrative of the present invention and is not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiment or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.