Patent Publication Number: US-8122569-B2

Title: Auxiliary handle for hand-held power tool

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an auxiliary handle for a hand-held power tool such as a power drill, a hammer drill or a chisel hammer and includes an attachment section for securing the auxiliary handle on a section of the power tool and having an articulation section, a gripping member for holding the auxiliary handle and having at least one bearing section, a lockable lag hinge provided between the attachment section and the gripping member and having a pivot axis, and a locking device for locking and releasing the lag hinge. 
     2. Description of the Prior Art 
     In power tools, auxiliary handles of the type described above are provided, if needed, in form of a side handle mounted, e.g., on a housing section adjacent to a tool holder for guiding the power tool. It is known to form a gripping member of the auxiliary handle pivotable about a pivot axis in order to optimally guide the power tool and to enable different griping positions of the auxiliary handle on the power tool, which would insure a less tiring operation. A lag hinge provides for a pivotal movement of the gripping member relative to the attachment section of the auxiliary handle. The pivoting of the gripping member permits to adjust the gravity point of the power tool with respect to the tool user. Often, the gripping member is adjusted during the power tool use. German Publication DE 10 2006 055 524 A1 discloses an auxiliary handle for a hand-held power tool and having its attachment section formed as a clamping sleeve for mounting the auxiliary handle on a section of the power tool. The attachment section also includes an articulation section. The auxiliary handle also includes a gripping member for grasping and holding the auxiliary handle and having spaced from each other bearing sections. Between the attachment section and the gripping member, a lockable lag hinge is arranged. The lag hinge has a pivot pin a longitudinal axis of which forms the pivot axis of the lag hinge. The bearing sections of the gripping member and the articulation section of the attachment section are provided, in the region where their respective contact surface contact each other, respectively, with toothing and counter-toothing which form a locking device and which lock the lag hinge when the toothing and counter-toothing formlockingly engage each other, and which release the lag hinge in their disengaged condition. The auxiliary handle is locked or released with an operational knob that forms a locking member and is arranged on one end of the pivot pin of the lag hinge, being secured on a section of the pivot pin provided with an outer thread, with the locking device being displaced in its locking or release position, respectively. 
     The drawback of the above-described auxiliary handle consists in that for releasing the lag hinge, the engaging each other elements of the locking device should be spaced from each other by at least the height of the teeth so that the gripping member can be pivoted relative to the attachment section. This requires several revolutions of the locking member which, in turn, increases the time necessary for adjustment. 
     Further, during release of the lag hinge, the locking and, thus, fixation of the attachment section of the auxiliary handle on the power tool can also be loosen, and the auxiliary handle, which is mounted on the power tool, can automatically pivot about an operational axis defined by a working tool. Therefore, with a new locking of the lag hinge, additionally, a proper orientation of the entire auxiliary handle relative to the power tool should be carefully readjusted. 
     Accordingly, an object of the present invention is an auxiliary handle for a hand-held power tool in which the above-discussed drawbacks of a known auxiliary handle are eliminated. 
     Another object of the present invention is an auxiliary handle for a hand-held power tool and that would enable a simple and rapid pivoting of the gripping member. 
     SUMMARY OF THE INVENTION 
     These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a locking device including a locking member pivotable about an axis extending parallel to the axis of the lag hinge between a locking position in which it locks the lag hinge, and a release position in which the lag hinge is released. 
     The pivot axis of the lag hinge, e.g., corresponds to a longitudinal axis of a pivot pin that extends, at least partially, through the articulation section of the attachment section and at least one bearing section of the gripping member. 
     Thereby, the articulation section and the at least one bearing section, through which the pivot pin extends, form articulation sleeves of the lag hinge. The blocking or release of the lag hinge is carried out by pivoting the locking member about its axis. The axis is formed by, e.g., a support pin provided in a pivot point and a longitudinal axis of which extends parallel to the pivot axis of the lag hinge. The function of the auxiliary handle, which is associated with pivotability of the gripping member relative to the operational direction, is completely detached from other functions of the auxiliary handle. 
     Thus, the lag hinge locking device is completely independent from the locking device of the auxiliary handle, so that for pivoting the gripping member, the locking device of the auxiliary handle need not be released any more. In particular, with an auxiliary handle that is locked by an operational element acting in the direction of the pivot axis, the use of the inventive locking device for locking the lag hinge is advantageous. After the gripping member has been pivoted about a pivot axis in a desired position relative to the power tool, the locking member is pivoted toward the pivot axis in its locking position so that the release condition of the lag hinge is eliminated, and the lag hinge is locked again. 
     Advantageously, the locking member includes a safety element for securing the locking member in the locking position. The safety element prevents and inadvertent release of the locking device. The safety element is advantageously formed as a locking element such as a cam or projection that engages in a complementary locking element such as a groove or recess for securing the locking member in its locking position. 
     Advantageously, the locking member is supported on the articulation section of the attachment section. This provides for an advantageous manufacturing of the locking device and, thereby, of the auxiliary handle. In its locking position, the locking member engages a section of the at least one bearing section of the gripping member, preventing an inadvertent pivotal movement of the gripping member relative to the attachment section of the auxiliary handle during operation or transportation of the power tool. 
     According to an alternative embodiment, the locking member is arranged on the at least one bearing section of the gripping member. In this case, the locking member engages, in its locking position, a section of the articulation section of the attachment section, locking the lag hinge. 
     Advantageous, the locking member includes locking means that cooperates, in the locking position of the locking member, with counter-locking means provided on the at least one bearing section of the gripping member. Thereby, a formlocking connection between these elements of the auxiliary handle becomes available. This connection enables transmission of the large forces. In the alternative embodiment described above, the counter-locking means is provided on the bearing section of the gripping member. 
     Advantageously, the articulation section of the attachment section is likewise provided with counter-locking means with which the locking means of the locking member cooperates in the locking position of the locking member. The resulting formlocking connection permits to transmit larger forces between the elements of the auxiliary handle in the locking position of the locking member than at a frictional connection between the elements of the auxiliary handle. 
     Advantageously, the locking means of the locking member has elevations in form of cams and the counter-locking means of the articulation section and of the at least one bearing section have corresponding recesses for receiving the cams. This insures an advantageous connection in the locking position of the locking member. With the articulation section of the attachment section and the at least one bearing section of the gripping member being provided with counter-locking means in form of recesses, the locking means, which is formed as cams or elevations, advantageously is so arranged on the locking member that the locking means is capable of engaging in the counter-locking means in different positions of the gripping member relative to the attachment section. 
     Advantageously, the counter-locking means of both the articulation section of attachment section and of the at least one bearing section of the gripping member have a plurality of locking element radially circumferentially spaced from each other and provided in a grid. The grid determines the stepwise pivotability of the gripping member relative to the attachment section. Advantageously, the locking means on the locking member also has locking elements spaced from each other and arranged in a grid corresponding to the grid of the counter-locking elements. 
     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 plan view of a hand-held power tool with an auxiliary handle according to the present invention; 
         FIG. 2  a side view of the auxiliary handle according to the present invention; 
         FIG. 3   a  a cross-sectional view along line III-III in  FIG. 2  of auxiliary handle with the locking device in the locking position; 
         FIG. 3   b  a cross-sectional view similar to that of  FIG. 3   a  but with the locking device in its release position; 
         FIG. 4   a  a cross-sectional view along line IV-IV in  FIG. 2  of the auxiliary handle with the locking device in its locking position; and 
         FIG. 4   b  a cross-sectional view similar to that of  FIG. 4   a  but with the locking device in its release position. 
     
    
    
     In the drawings, the same parts are designated with the same reference numerals. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A hand-held power tool  7 , which is shown in  FIG. 1 , includes an auxiliary handle  11  according to the present invention that is formed as a side handle and is releasably secured on a cylindrical section  8  of the power tool  7 . The auxiliary handle  11  has a gripping member  31  for grasping and holding the auxiliary handle  11  and pivotable about a pivot axis  12  toward an operational axis  9  of the power tool  7  to adapt to the gripping position on the power tool  7 , when needed. 
     The auxiliary handle  11 , which is shown in detail in  FIGS. 2-4   b , has an attachment section  21  for securing the auxiliary handle  11  on the power tool  7  and two, pre-loaded against each other, clamping sections  22 . The clamping sections  22  are securable on the cylindrical section  8  by a clamping device  23  formed by a clamping screw and a nut. In a loosened position of the clamping sections  22 , the auxiliary handle  11  is pivotable about the operational axis  9  of the power tool  7  or can be removed from the power tool  7 . The attachment section  21  has an articulation section  24 . The gripping member  31  of the auxiliary handle  11  is essentially U- or D-shaped and has a base  32  and two legs  33  and  38  projecting from the base  32 . On the leg  33 , there is provided a first bearing section  34  adjacent to the second leg  38 , and on the leg  38 , there is provided a second bearing section  39  adjacent to the leg  33 . 
     Between the attachment section  21  and the gripping member  31 , there is provided a lockable lag hinge  46  having a pivot pin  47  having a longitudinal axis that forms the pivot axis  12 . The pivot pin  47  extends through the articulation section  24  and both bearing sections  34  and  39 , so that these sections form articulation sleeves of the lag hinge  46 . 
     There is further provided a locking device  51  for locking or releasing the lag hinge  46 . The locking device  51  has a locking member  52  pivotable about an axis  53  extending parallel to the pivot axis  12  and pivotable between a locking position in which the lag hinge  46  is locked, and a release position in which the lag hinge is released. The locking member  52  is supported on the articulation section  24  of the attachment section  21 . The axis  53  is formed by a pivot pin extending parallel to the pivot axis  12 . 
     The locking member  52  has, in the extension direction of the pivot axis  12 , a width B which is greater than the width of the articulated section  24  in the same direction. The locking member  52  extends beyond the articulation section  24  on both sides of the articulation section  24 . In the locking position of the locking member  52 , it bears against the articulation section  24  of the attachment section  21 , on one hand, and against edge regions of both bearing sections  34  and  39 , on the other hand. 
     The locking member  52  has four locking elements  54  formed as projecting cams. In the locking position of the locking member  52 , the locking elements  54  engage in four of fifteen counter-locking elements  35  formed as recesses in the bearing sections  34  and  39  of the gripping member  31 , and engage in four of five counter-locking elements  25  formed as recesses in the articulation section  24  of the attachment section  21  in accordance with orientation of the gripping member  31  relative to the attachment section  21 . The counter-locking elements  25  and  35  are circumferentially and radially spaced from each other in a respective grid. The locking elements  54  are likewise correspondingly spaced from each other in a grid corresponding to the grids of the counter-locking elements  25  and  35 . The locking means  54  extend essentially over the entire width B of the locking member  52 . When the counter-locking elements  25  and  35  are arranged in a line, then a locking element  53  simultaneously engage in respective counter-locking element  25  and counter-locking element  35  in a locking position of the locking member  52 . 
     On the locking member  52 , there is further provided a safety element  56  for securing the locking member  52  in its locking position. The safety element  56  is pivotally secured at a pivot point  57  provided on the locking member  52  and engages in, its safety position, with a projection  58  provided on the safety element  56 , in a safety groove  26  provided on the articulation section  24  of the attachment section  21 . The safety element  56  is so arranged on the locking member  52  that without a manual pivotal movement of the safety element  56  about its operational section  59 , at an inadvertent lifting of the locking member  52  off the articulation section  24  of the attachment section  21 , the safety elements  56  counter-acts the lifting-off of the locking member  52 . Thereby, an advantageous locking of the locking member  52  in its locking position is insured. 
     For pivoting the gripping member  31  relative to the attachment section  21 , firstly, the safety element  56  is displaced in its releasing position in which the locking member  52  can be pivoted about its axis  53  away from the articulation section  24  of the attachment section  21 . Thereby, the engagement of the locking elements  54  with the counter-locking elements  25  and  35  on the articulation section  24  and the bearing sections  34  and  39 , respectively, is lifted off. As a result, the locking member  52  is in its release position in which the lag hinge  46  is released, so that pivoting of the gripping member  31  relative t to the attachment section  21  becomes possible. 
     For a new locking of the lag hinge  46 , the locking member  52  is again pivoted toward the articulation section  24  of the attachment section  21  so that, with a corresponding alignment of the counter-locking elements  35  on the bearing sections  34  and  39  and with the counter-locking elements  25  on the articulation section  24 , the locking elements  54  again engage the counter-locking elements  25  and  35 . The locking member  52  occupies its locking position in which the lag hinge is locked. 
     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.