Abstract:
A hand-held drive-in tool ( 10 ) has a trigger switch ( 19 ) for triggering a drive-in process by drive unit ( 30 ) that drives a drive-in ram ( 13 ), a press-on feeler ( 18 ) which is arranged so as to be displaceable at a muzzle ( 16 ), which can detect that the drive-in tool pressed against a workpiece, and which prevents the actuation of a drive-in process in its initial position ( 41 ) and enables actuation of its drive-in process in its switching position ( 43 ), a component feeler ( 17 ) displaceably arranged at the muzzle ( 16 ) and capable of being actuated independently from the press-on feeler ( 18 ) and preventing actuation of a drive-in process in its initial position ( 42 ) and enabling the actuation of the drive-in process in its switching position ( 44 ), the component feeler ( 17 ) detecting fitting of an auxiliary constructional component ( 110 ) to the muzzle ( 16 ), with a drive-in process being initiated by the trigger switch ( 19 ) only when the component feeler ( 17 ) and the press-on feeler ( 18 ) are both in their respective switching positions ( 43, 44 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a hand-held fastener drive-in tool. 
         [0003]    2. Description of the Prior Art 
         [0004]    In hand-held fastener drive-in tools of the kind mentioned above, the driving energy is produced from, e.g., liquid or gaseous fuels or electrical energy stored, for example, in a battery. The drive-in tools have a displaceable drive-in ram with which fasteners can be driven into a workpiece. 
         [0005]    German Publication DE 10 2005 000 089 A1 discloses a hand-held fastener drive-in tool having a drive unit for driving a drive-in ram which is displaceably mounted in a guide. The drive unit has at least one drive spring which can be tensioned by an electrically operated tensioning device. A press-on feeler that cooperates with switching means, is arranged at a muzzle of the fastener drive-in tool. The switching means is electrically connected to a control unit by a conductor. The switching means itself sends an electric signal to the control unit as soon as the press-on feeler is actuated in response to the fastener drive-in tool being pressed against a workpiece. This ensures that the fastener drive-in tool can only be actuated when it has been properly pressed against a workpiece or the like. 
         [0006]    A fastener drive-in tool of this type is only conditionally suitable for mounting an auxiliary constructional component, e.g., a cable binder or formwork stop, on the muzzle prior to a drive-in process because, in this case, the switching means will be actuated already before pressing against a workpiece. 
       SUMMARY OF THE INVENTION 
       [0007]    It is the object of the present invention to improve a fastener drive-in tool of the type mentioned above in such a way that auxiliary constructional components can be fitted to the muzzle and detected and in which it is possible at the same time to detect when the device is pressed against a workpiece or a constructional component. 
         [0008]    This and other objects of the present invention which will become apparent hereinafter are achieved by providing a drive-in tool in which a component feeler is displaceably arranged on the muzzle, is actuated independently from the press-on feeler, prevents actuation of a drive-in process in its initial position, and enables actuation of a drive-in process in its switching position. The component feeler permits to detect the fitting of an auxiliary constructional component to the muzzle, with a drive-in process being initiated by an actuation switch only when the component feeler and the press-on feeler are both in their respective switching positions. 
         [0009]    On one hand, this makes it possible for the fastener drive-in tool to detect that an auxiliary constructional component has been properly fitted to the muzzle. On the other hand, subsequent pressing of the fastener drive-in tool against a workpiece or constructional component is detected, whereby pressing against a workpiece is detected by the press-on feeler through or via the auxiliary constructional component. The auxiliary constructional component can, for example, be formed as a formwork stop, spacer, reinforcement holder, pipe clamp, holding element, angle element, ceiling hanger, or the like. 
         [0010]    In an advantageous manner, the component feeler can be moved from its initial position into its switching position by an actuating contour of the auxiliary constructional component so as to ensure a reliable detection of the auxiliary constructional component when correctly fitted to the muzzle. 
         [0011]    It is further advantageous when the press-on feeler can be moved from its initial position into its switching position by a displaceably guided sensing element of the auxiliary constructional component. The press-on movement can be conveyed to the press-on feeler of the fastener drive-in tool in a simple manner by the displaceable sensing element. 
         [0012]    It is also advantageous when the component feeler and the press-on feeler are sleeve-shaped, both of them being guided in the muzzle concentric to one another. A functionally simple and compact construction is achieved in this way. 
         [0013]    In an advantageous further development, the component feeler is arranged inside the second press-on feeler and comprises a drive-in channel for fasteners. This makes it possible to arrange the actuating contour of the auxiliary constructional component in the area of its guide sleeve for the fastener and which is usually inserted into the muzzle to secure the auxiliary constructional component to the muzzle. 
         [0014]    In an advantageous manner, the drive-in process can be triggered by the trigger switch only when the component feeler is moved into its switching position at least 0.3 seconds before the press-on feeler. This step makes it appreciably more difficult to tamper with or bypass the safety device with the press-on feeler and component feeler. 
         [0015]    Further, it is advantageous when an electric control unit is provided, and a first electric switch is associated with the component feeler, and a second electric switch is associated with the press-on feeler. The two switches are connected to the control unit, and the control unit monitors the sequence and the time interval between the switching signals of the first switch and second switch. The monitoring of the sequence makes it highly difficult to circumvent the safety system. 
         [0016]    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 embodiments when read with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS: 
         [0017]    The drawings show: 
           [0018]      FIG. 1  a longitudinal cross-sectional view of a fastener drive-in tool according to the present invention in its initial position; 
           [0019]      FIG. 2  a cross-sectional view of an auxiliary constructional component at a muzzle of the fastener drive-in tool according to  FIG. 1 ; and 
           [0020]      FIG. 3  a cross-sectional view of the auxiliary constructional component shown in  FIG. 2  at the muzzle of the fastener drive-in tool and positioned against a workpiece. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    A fastener drive-in tool according to the present invention which is shown in  FIGS. 1 and 2 , is formed as an electrically operated fastener drive-in tool  10  which is outfitted with a self-contained power supply. The fastener drive-in tool  10  has a housing  11  and a drive unit designated in its entirety by a reference numeral  30  and located in the housing  11  for driving a drive-in ram  13  which is displaceably guided in a guide  12 . The drive-in ram  13  has a drive-in portion  14  for a fastener  130  and a head portion  15 . 
         [0022]    Adjoining the end of the guide  12  extending in the drive-in direction  27  is a muzzle  16  having a guide channel  26  extending coaxially to the guide. 
         [0023]    The drive unit  30  contains a driving spring  31  which is supported at one of its ends indirectly against the housing  11  and the other end of which engages the head portion  15  of the drive-in ram  13 . 
         [0024]    In the initial position  22  of the drive-in ram  13  shown in  FIG. 1 , the drive-in ram  13  is elastically preloaded against the driving spring  31 . 
         [0025]    In the initial position  22 , the drive-in ram  13  is held by a locking device, which is designated in its entirety by a reference numeral  50 , has a pawl  51  that engages at a locking face  53  of a projection  58  of the drive-in ram  13  in a locking position  54  (see  FIG. 1 ), and holds this drive-in ram  13  against the force of the drive spring  31 . The pawl  51  is supported at an actuating motor  52  and can be moved by the latter into a release position, not shown in  FIG. 1 , as will be described more fully further below. The actuating motor  52  is connected to an electric control unit  23  by a first electric control line  56 . 
         [0026]    The fastener drive-in tool  10  also has a handle  20  on which a trigger switch  19  is arranged for actuating a drive-in process with the fastener drive-in tool  10 . Further, a power supply, which is designated in its entirety by a reference numeral  21  and which supplies the fastener drive-in tool  10  with electrical power, is arranged in the handle  20 . In the present case, the power supply  21  contains at least one battery, e.g., a Ni-MH battery or Lithium-ion battery. The power supply  21  is connected by electric supply lines  24  to the control unit  23  and to the trigger switch  19 . Further, the control unit  23  is connected to the trigger switch  19  by a switch line  57 . 
         [0027]    A press-on feeler  18  and a component feeler  17 , both of which are formed so as to be sleeve-shaped and which are displaceably guided in an expanded portion of the guide channel  26  of the muzzle  16 , are arranged at the muzzle  16  of the fastener drive-in tool  10 . In  FIG. 1 , the component feeler  17  and the press-on feeler  18  are shown in their respective initial positions  41 ,  42 . The internal component feeler  17 , which comprises a drive-in channel for fasteners, is connected to first actuating means  28   a  which is designed to actuate a first electric switch  29   a  when the component feeler  17  is moved in a direction opposite to the setting direction  27  into its switching position  42  (see  FIG. 2 ). 
         [0028]    The press-on feeler  18  which is arranged between the component feeler  17  and the muzzle  16 , is connected to a second actuating element  28   b  which is designed to actuate a second electric switch  29   b  when the press-on feeler  18  is moved in a direction opposite the setting direction  27  until its switching position  44  is reached (see  FIG. 3 ). An actuation of a setting process with the trigger switch  19  is only possible when both switches  29   a,    29   b  are actuated in the sequence of, first, the component feeler  17  and, second, the press-on feeler  18 . The first switch  29   a  must be actuated first, and the second switch  29   b  must then be actuated after a delay of at least 0.3 seconds. 
         [0029]    The switches  29   a,    29   b , are electrically connected to the control unit  23  by a switch line  25 . 
         [0030]    Further, a tensioning device, designated in its entirety by a reference numeral  70 , is provided in the fastener drive-in tool  10 . This tensioning device  70  includes a motor  71  which drives a drive roller  72 . The motor  71  is electrically connected to the control unit  23  by a second control line  74  and can be set in operation, e.g., when the drive-in ram  13  is in its end position in the drive-in direction  27  or when the fastener drive-in tool is lifted again from the workpiece W. The motor  71  has output means  75 , such as a driven wheel, which can be coupled to the drive roller  72 . The drive roller  72  is rotatably mounted on a longitudinally displaceable actuating arm  78  of actuation means  76  formed as a solenoid. The actuation means  76  is connected to the control unit  23  by an actuating line  77 . During operation, the drive roller  72  rotates in the direction of arrow  73  indicated by a dash line. 
         [0031]    When the fastener drive-in tool  10  is set in operation by a main switch, not shown, the control unit  23  initially ensures that the drive-in ram  13  is located in its initial position  22  shown in  FIG. 1 . If this is not the case, the drive roller  72  is advanced by the actuating means  76  to the output means  75  which has already been set in rotation by the motor  71  and engages the latter. At the same time, the drive roller  72  engages the drive-in ram  13  so that the latter is displaced in direction of the drive unit  30  by the drive roller  72  rotating in the direction indicated by arrow  73 . Thereby, the drive spring  31  of the drive unit  30  is tensioned. When the drive-in ram  13  has reached its initial position  22 , the pawl  51  of the locking device  50  engages in the locking face  53  at the drive-in ram  13  and holds it in the initial position  22 . The motor  71  can then be switched off by the control unit  23 , and the actuating means  76 , which is also controlled by the control unit  23 , moves the drive roller  72 , from its engaged position with the output means  75  and drive-in ram  13  to its disengaged position. 
         [0032]    To return the drive-in ram  13  and to preload the drive spring  31 , the tensioning device  70  is actuated at the end of the drive-in process by the control unit  23  when the fastener drive-in tool  10  is lifted again off the workpiece W. For this purpose, at least one of the switches  29   a,    29   b  supplies a signal to the control unit  23 . The drive-in ram  13  is moved by the tensioning device  70  against the drive spring  31  of the drive unit  30 , as was already described, and the drive spring  31  is preloaded again until the pawl  51  engages again, in its locking position  54 , the locking face  53  at the drive-in ram  13 . 
         [0033]      FIGS. 2 and 3  show an auxiliary constructional component  110  which is formed as a cable fastener or cable binder and which is arranged at the muzzle  16  of the fastener drive-in tool  10  described above. The auxiliary constructional component  110  has a base  111  at which a tie guide  117  for a cable tie, not shown in the drawings, is arranged laterally of the base  111  for fastening cables. A sleeve-shaped guide section  112  that has a through-opening  113  surrounded by an abutment  114  for a fastener  130 , projects from the base  111 . An actuating contour  115  is arranged at the guide section  112 . As can be seen in  FIGS. 2 and 3 , the component feeler  17  at the muzzle  16  of the fastener drive-in tool  10  can be actuated in direction of the second arrow  152  by the actuating contour  115  when the auxiliary constructional component  110  is fitted to the muzzle  16  in direction of the first arrow  151  (see  FIG. 2 ). The actuation of the component feeler  17  of the fastener drive-in tool  10  until it reaches its initial position  42  sets the control unit  23  of the fastener drive-in tool  10  in the standby state by actuating the first switch  29   a.    
         [0034]    Also arranged in the guide section  112  is a guide  116  for a sensing element  120  which is formed as an elongated hollow pin. The sensing element  120  has an axially extending receiving space  123  in which the fastener  130  is inserted and where it is held by frictional engagement. The sensing element  120  has three projections  122  which project radially from the central pin body and which are arranged at uniform distances from one another. Actuating surfaces  121  which actuate the press-on feeler  18  in the muzzle  16  of the fastener drive-in tool  10 , are arranged, as is shown in  FIG. 4 , on the sides of the projections  122  facing in the direction of mounting of the auxiliary constructional component  110  on the muzzle  16 . When the fastener drive-in tool  10  is pressed against a workpiece W with the auxiliary constructional component  110  mounted on the muzzle  16 , the sensing element  120  is displaced from its initial state shown in  FIG. 2  in direction of the third arrow  153  toward the muzzle  16 . As a result, the actuating surfaces  121  of the projections  122  move the press-on feeler  18  in the direction indicated by the fourth arrow  154  into the muzzle  16  (see  FIG. 3 ) until it reaches its switching position  44 . By moving the press-on feeler  18  into its switching position  44 , the second switch  29   b  is actuated, and the control unit  23  of the fastener drive-in tool  10  is ready to operate so that only the trigger switch  19  of the fastener drive-in tool  10  needs to be actuated to initiate a setting process. However, this operation-ready state is only initiated by the control unit  23  when the first switch  29   a  and second switch  29   b  are actuated with a delay of at least 0.3 seconds and in the sequence of first switch  29   a  being actuated first and second switch  29   b  being actuated second. This rules out any tampering with the safety device that includes the press-on feeler  18  and component feeler  17 . When the trigger switch  19  is actuated by the user, the locking device  50  is moved into its release position (not shown in the drawings) by the control unit  23 , whereby the pawl  51  is lifted from the locking face  53  at the drive-in ram  13  by the actuating motor  52 . The drive-in ram  13  is then moved in the drive-in direction  27  by the drive spring  31  of the drive unit  30  and a fastener  130  is driven into the workpiece W. 
         [0035]    Of course, the auxiliary constructional component  110  can also be formed as a formwork stop, spacer, reinforcement holder, pipe clamp, holding element, angle element, ceiling hanger, or the like. 
         [0036]    Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are 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 embodiments 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.