Abstract:
A combustion-operated setting tool for driving fastening elements in a constructional component includes a device ( 30 ) for adjusting setting energy applied to a setting piston ( 15 ) axially displaceable in a guide space ( 4 ) of a piston guide ( 13 ). The adjusting device ( 30 ) has a separation member ( 31 ) adjustably arranged between the receptacle ( 18 ) and the guide space ( 14 ) of the piston guide ( 13 ) and dividing the combustion chamber ( 20 ) in a first sub-chamber ( 21 ) arranged between the receptacle ( 18 ) and the separation member ( 31 ) and a second sub-chamber ( 22 ) arranged between the separation member ( 31 ) and the guide space ( 14 ) of the piston guide ( 13 ), the separation member ( 31 ) having a plurality of through-openings ( 34, 35 ) for controlling flow of the combustion gases into the guide space ( 14 ) of the piston guide ( 13 ), with an active opening cross-section of at least a portion of the through-openings ( 34, 35 ) changing dependent on an adjustable position of the separation member ( 31 ).

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a combustion-operating setting tool for driving fastening elements in a constructional component and including a piston guide, a setting piston displaceably arranged in the guide space of the piston guide, a combustion chamber adjoining the piston guide, a receptacle for receiving a propellant charge and adjoining the combustion chamber at an end of the combustion chamber remote from the piston guide, a separation member adjustably arranged between the receptacle and the guide space of the piston guide and dividing the combustion chamber in a first sub-chamber arranged between the receptacle and the separation member and a second sub-chamber arranged between the separation member and the guide space of the piston guide with the separation member having a plurality of through-openings for communicating flow of the combustion gases into the guide space of the piston guide and having an active opening cross-section, and a device for adjusting the setting energy by controlling the combustion gases applied to the setting piston. 
   2. Description of the Prior Art 
   Setting tools of the type described above are driven with solid fuels in a powder or pellet form, with the setting piston being driven by combustion gases generated as a result of fuel combustion. With the setting piston, fastening elements can be driven in a constructional component. 
   German Publication DE 199 83 546 A1 discloses a hand-held, powder charge-operated setting tool in which a setting piston is displaceable in a guide space of a piston guide. At one end of the piston guide, which is formed as a guide cylinder, there is provided a receptacle for receiving a propellant charge and which is adjoined, in the direction of the setting piston, by a combustion chamber. The combustion chamber is divided by a separation member, which is formed as a plate with a plurality of openings. The separation member is fixedly secured in the inner space of the guide cylinder. The setting tool also includes a device for changing the driving force. The changing device adjusts the volume of a portion of the combustion chamber that is adjacent to the setting piston. To this end, the changing or adjusting device has a power adjusting arm arranged on the setting piston and which is engaged by adjusting means in form of a screw. With the adjusting arm, the upper end position of the setting piston and, thus, the volume of the second sub-chamber above the setting piston can be adjusted. According to another embodiment, sidewise of the second sub-chamber, there is provided an additional chamber that is connected with the combustion chamber by an adjustable valve. The volume of the additional chamber is adjusted with a displaceable plate that forms a wall of the additional chamber. 
   The drawback of the adjusting device consists in that a number of additional measures need be taken which require an additional constructional space and noticeably increase the production costs. 
   Accordingly, an object of the present invention is a setting tool of the type described above in which the drawbacks of the known setting tool are eliminated and a simple setting energy regulation is achieved. 
   SUMMARY OF THE INVENTION 
   This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a setting tool in which the guide, dividing the combustion chamber in a first sub-chamber arranged between the receptacle and the separation member and a second sub-chamber arranged between the separation member and the guide space of the piston guide, with the separation member having a plurality of through-openings for controlling flow of the combustion gases into the guide space of the piston guide, with the through-openings having an active opening cross-section, and with an active opening cross-section of at least a portion of the through-openings changing dependent on an adjustable position of the separation member. 
   Due to the fact that at least a portion of the through-openings is closed partially or completely dependent on the position of the separation member, their active opening cross-section, which limits the flow of the combustion gases through the through-openings, can be reduced or even closed completely. With such a separation member, the energy, which is produced by the propellant charge and is applied to the setting piston, can be easily controlled by changing the active opening cross-section, substantially without using means that would require additional constructional space. Further, the used means is cost-effective, as only a very small adaptation any few additional parts are needed. 
   It is advantageous, when the piston guide is provided with channels, and at least a portion of the through-openings of the separation member can be displaced relative to the channels of the piston guide. Thereby, the control and, if needed, splitting of the combustion gases can be easily achieved. The channels can be formed as release channels or as channels extending in a direction of the guide space. 
   The separation member can be easily adjusted when it is supported for a pivotal movement parallel to the longitudinal axis of the piston guide. To this end, the separation member is provided with a circular disc-shaped base body easily adjustable by rotation. The separation member can be connected with an adjusting member with which a position of the separation member can be adjusted. 
   Advantageously, the plurality of through-openings of the separation member includes first through-openings extending through the separation member parallel to an axis of the piston guide for conducting the combustion gases from the first sub-chamber into the second sub-chamber. Thereby, the path of the combustion gases is not obstructed even when a portion of the combustion gases is released in the environment through corresponding further through-openings and, if needed, channels. 
   It is advantageous when there is provided a counter-member arranged in the piston guide in an abutting relationship with the separation member and having a plurality of channels. With the counter-member, in a simple way, the through-openings of the separation member can be partially or completely closed, with a possible reduction of the active opening cross-section to zero, dependent on the adjustable position of the separation member. Advantageously, the plurality of channels of the counter-member includes first channels extending parallel to a longitudinal axis of the piston guide through the counter-member for conducting the combustion gases form the first sub-chamber to the second sub-chamber. The first channels of the counter-member can partially or completely overlap the first through-openings of the separation member, dependent on the position of the separation member, whereby the active opening cross-section of the first through-openings of the separation member can be controlled. 
   It is further advantageous when the plurality of channels of the counter-member includes second channels that open at their ends remote from the separation member into release channels formed in the piston guide and can be brought into an overlapping relationship with some of the plurality of the through-openings of the separation member for releasing into environment at least a portion of the combustion gases from the first sub-chamber. 
   This prevents, in particular, over-high pressure in the first sub-chamber of the combustion chamber when the first through-openings of the separation member are partially closed, and their active opening cross-section is reduced. A maximal setting energy from the propellant charge can be obtained when the first through-openings of the separation member, which lead to the guide space, are completely open, and no combustion gases are released in the environment. The setting energy, however, is reduced when the combustion gases are released in the environment and/or the active opening cross-section that leads to the guide space, is reduced. 
   It is further advantageous when, in the absence of the counter-member, the separation member has a cylindrical section that extends coaxially with a longitudinal axis of the piston guide and has two through-openings formed in its cylindrical wall and radial outer ends of which can be brought in an overlapping relationship with release channels formed in the piston guide for releasing into environment at least a portion of the combustion gases from the second sub-chamber. The reduction of the setting energy is effected only by releasing the combustion gases in the environment. Thus, the maximal setting energy of the propellant charge can be obtained when no combustion gases are released in the environment. The setting energy, however, is reduced when the combustion gases are released in the environment. 
   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 
     The drawings show: 
       FIG. 1  a cross-sectional view of a first embodiment of a setting tool according to the present invention in a condition, in which the tool is pressed against a constructional component, and with first energy adjustment; 
       FIG. 2  a partial cross-sectional view of the setting tool shown in  FIG. 1  at an increased, in comparison with  FIG. 1 , scale, with a second energy adjustment; 
       FIG. 3  a partial cross-sectional view of a second embodiment of a setting tool according to the present invention in a condition, in which the tool is pressed against a constructional component, and with first energy adjustment; 
       FIG. 4  a partial cross-sectional view of the setting tool shown in  FIG. 3  with a second energy adjustment; 
       FIG. 5  a cross-sectional view along line V-V in  FIG. 3 ; and 
       FIG. 6  a cross-sectional view along line VI-VI in  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A combustion-operated setting tool  10  according to the present invention, which is shown in  FIGS. 1-2 , has a housing  11 , a one- or multi-part sleeve-shaped member  12  located in the housing  11 , and a piston guide  13  displaceably arranged in the sleeve-shaped member  12 . A setting piston  15  is arranged in the guide space  14  of the piston guide  13  for an axial displacement therein. The piston  14  is driven by a propellant charge  41  such as, e.g., a blister cartridge received in a receptacle  18 , e.g., a cartridge socket. The propellant charge  41  can be arranged, together with further propellant charges on a magazine strip. The receptacle  18  is formed in an annular support part  40  received in a first receiving chamber  26  provided at the end of the piston guide  13 . In a press-on position of the setting tool  10  against a constructional component, which is shown in  FIGS. 1-2 , the receptacle  18  is closed with a bottom  17 , and the propellant charge  41  becomes closed in a chamber of the receptacle  18 . Preferably, the support part  40  is formed as a sealing bush. The propellant charge  41  is ignited with an ignition unit, not shown. The ignition unit can be activated electronically or mechanically, e.g., with an elastically operating spark plug. Actuation of the ignition unit is effected with an actuation switch  16  provided on the handle  19  of the setting tool  10 . A combustion chamber  20  is provided between the bottom  17  and the guide space  14 . The combustion of the propellant charge  41  after its ignition takes place in the combustion chamber  20 . 
   The setting tool  10  further includes a device for adjusting the setting energy generally designated with a reference numeral  30 . The energy-adjusting device  30  has a separation member  31  that divides the combustion chamber  20  in a first sub-chamber  21  adjacent to the bottom  11 , and a second sub-chamber  22  adjacent to the guide space  14 . The separation member  31  pivots about a pivot axis extending parallel to a longitudinal axis A defined by the combustion space  14 . The separation member  31  has a base body  32  in form of an annular plate or a circular disc. The circular disc-shaped base body  32 , which is arranged in the first receiving chamber  26  of the piston guide  13  and directly adjoins the support part  17 , has first through-opening  34  which extend parallel to the longitudinal axis A and connect the first sub-chamber  21  of the combustion chamber  20  with a second sub-chamber  22 . The separation member  31  further has a cylindrical section  33  extending in a second receiving chamber  27  of the piston guide  13 . The cylindrical section  33  is coaxial with the circular disc-shaped base body  32 . In the cylindrical wall of the cylindrical section  33 , there are provided second through-openings  35  which can be brought in an overlapping relationship with channels  28  in the piston guide  13  which are formed as release channels. The channels  28  are connected with the environment over sleeve openings  24  and housing openings  23  and further over release housing openings  25 . 
   The separation member  31  can be manually pivoted with an adjusting member  36  that branches out of the circular disc-shaped base body  32  and extends through a slot  29  in the piston guide  13 . The pivotal movement of the separation member  31  changes the position of the second through-openings  35  relative to the channels  28  and, thereby, an active opening cross-section of the through-openings  35  through which the combustion gases flow. 
   In  FIG. 1 , the separation member  31  is shown in a first position in which the second through-openings  35  do not open into the channels  28 , and the active opening cross-section of the second through-openings  35  is zero. Upon ignition of the propellant charge  41 , the expanding combustion gases flow in the direction of arrows  44 ,  45 , completely acting on the setting piston  15 . In this position, the maximal combustion energy is imparted to the setting piston  15 . 
     FIG. 2  shows a second position of the separation member  31  in which the second through-openings  35  completely overlap the channels  28 , completely opening thereinto. Therefore, the active opening cross-section of the through-openings  35  is at its maximum. Upon ignition of the propellant charge  41 , the expandable gases firstly, flow in the direction of arrow  44  and then in the direction of arrows  45 ,  46 , dividing the gas stream. Thereby, the action of combustion gases on the setting piston  15  is reduced. In this position of the separation member  31 , a minimal combustion energy is imparted to the setting piston  15  because a portion of the combustion gases flows from the second sub-chamber  22  of the combustion chamber  20  in the environment in the direction of arrow  46 . 
   By positioning the separation member  31  in intermediate positions with greater or smaller overlapping of the second through-openings  35  with the channels  28 , the setting energy can be adjusted between minimal and maximal setting energies. The first and second positions of the adjusting member  36  can be defined with appropriate stops. These stops are formed in the same way as stops  43  and  47  of another embodiment which is shown in  FIGS. 5-6 . 
   The manually operated adjusting member can be replaced with an automatic adjusting member that can be controlled with appropriate control means. In this case, an optimal energy adjustment is effected based on different setting parameters such as, e.g., type of the constructional component, the required setting depth, type of to-be-set fastening elements, etc. The adjusting member can also be provided on the support part and the pivotal movement can be transmitted from the support part to the separation member by an appropriate gear arrangement. Further, the support part and the separation member can be formed integrally with each other as a one-piece part. 
   A setting tool  10 , which is shown in  FIGS. 3-6 , differs from the previously discussed setting tool in that the energy-adjusting device  30  has a separation member  31  with a base body  32  that is formed with both first and second openings  34 ,  35  extending parallel to the longitudinal axis A and with the branched-out adjusting member  36 . In the second receiving chamber  27  of the setting piston guide  13 , the separation member  31  is arranged directly against a counter-member  37  which is formed as a perforated plate. In the plate  37 , there are formed first channels  28  extending parallel to the longitudinal axis A and second channels  39  which bend from axial direction in a radial direction. 
     FIGS. 3-5  show a position of the separation member  31  in which the setting tool  10  operates with the maximal setting energy. The adjusting member  36  of the separation member  31  abuts the stop  43 , whereby the first through-openings  34  of the separation member  31  are completely overlapped by the first channels  38  of the counter-member  37 , so that the active opening cross-section of the first through-openings  34  is maximal. The second through-openings  35  are not open in the second channels  39 , they are not overlapped by them. Their active cross-section is, therefore, zero. During a combustion process of a propellant charge  41  in the combustion chamber, the expanding combustion gases would flow only through the first through-openings  34  and the first channels  38  in the direction of arrows  44  and  45  completely in the direction toward the setting piston  15  which is, thus, driven with a maximal combustion energy. 
     FIGS. 4 and 6  show a position of the separation member  31  in which the setting tool  10  operates with a minimal energy. The adjusting member  36  of the separation member  31  abuts the stop  47 , and the first through-openings  34  of the separation member  31  are overlapped by the first channel  38  of the counter-member  37  by about 50%. The active opening cross-section of the first through-openings  34  is, thus, also amounts to about 50%. The second through-openings  35  open completely in the second channels  39  or are completely overlapped by them, and their active opening cross-section is maximal. Upon combustion of the propellant charge  41  in the combustion chamber, the expanding combustion gases flow through the first through-openings  34  and the first channels  38  of the counter-member  37  in the direction of arrows  44 ,  45  in the direction toward the setting piston  15 , on one hand and, on the other hand, flow through the second through-openings  35  and the second channels  39  as well as the first channels  38  into environment. Thus, the setting piston  15  is driven with a minimal energy. 
   Here, likewise, the separation member  31  can be positioned in intermediate positions, with the first through-openings  34  being overlapped with the first channels  38  of the counter-member  37  to a greater or lesser extent and the second through-openings  35  being overlapped with the second channels  39 , so that the setting energy can be stepwise adjusted between minimal and maximal possible energy. 
   The counter-member  37  can be formed integrally with the piston guide  13  as a one-piece part. With respect to other details of the embodiment shown  FIGS. 3-6 , not explicitly shown with reference numerals, reference should be made to the description of the embodiment shown in  FIGS. 1 and 2 . 
   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.