Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a manually guided implement, especially a pole pruner, a brush-cutter, a long-reach hedge trimmer, or the like.  
           [0002]    U.S. Pat. No. 4,122,601 discloses a manually guided implement that at one end of a supporting tube is provided with a drive motor that drives a working tool that is held at the other end of the supporting tube. The supporting tube is divided into longitudinal sections in order to be able to transport the implement in a compact form. The two sections of the supporting tube can be fixedly connected to one another with the aid of coupling elements that in the assembled state of the implement are disposed at respectively facing ends of the supporting tube. The working tool assumes a fixed angle relative to the supporting tube.  
           [0003]    Unfortunately, with the known manually guided implement it is not possible to adjust the working position nor the working tool in a manner specific to a particular application.  
           [0004]    It is therefore an object of the present invention to provide a manually guided implement that with a straightforward and economical construction makes it possible to adjust the working position of the working tool in a manner specific to the application at hand.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    This object, and other objects and advantages of the present invention, will appear more clearly from the following specification in conjunction with the accompanying schematic drawings, in which:  
         [0006]    [0006]FIG. 1 is a perspective view of one exemplary embodiment of an inventive manually guided implement;  
         [0007]    [0007]FIG. 2 is a perspective view of a miter gear on the supporting tube of the manually guided implement of FIG. 1;  
         [0008]    [0008]FIG. 3 is a longitudinal cross-sectional view through the miter gear of FIG. 2;  
         [0009]    [0009]FIG. 4 is a perspective view of a working tool of a pole pruner;  
         [0010]    [0010]FIG. 5 is a view of the working tool of FIG. 4 in a different working position;  
         [0011]    [0011]FIG. 6 is a view of the working tool of FIG. 5 in a different working position; 
     
    
     SUMMARY OF THE INVENTION  
       [0012]    The manually guided implement of the present invention is characterized primarily in that the sections of the supporting tube are fixedly interconnected via a gearbox of a miter gear at an angle that is prescribed by the gearbox and is smaller or greater than 180°.  
         [0013]    Due to the fact that the sections of the supporting tube can be rigidly interconnected by a gearbox of a miter gear at a fixed angle that is prescribed by the shape of the gearbox, and that is other than 180°, various angles of inclination or adjustment angles of the working tool relative to the supporting tube can be selected in a simple manner. In this way, different working positions of the tool and of the manually guided implement can be set and maintained.  
         [0014]    Pursuant to a preferred embodiment of the present invention, at least one end, and in particular both ends, of the supporting tube sections that face the gearbox, are respectively in engagement with a shaft on the gearbox. In this connection, the shaft can either extend into the gearbox or can project from the contour thereof. In this connection, it is expedient to monolithically embody the shafts with the gearbox. Depending upon the shape of the gearbox, especially as a function of the angular arrangement of the shafts relative to one another on the gearbox, the angle between the supporting tube sections is fixed. The miter gear is preferably surrounded by a spherical gearbox. It is expedient to form the gearbox from two housing portions that are symmetrical relative to one another. In this connection, the gearbox is expediently divided along a centerline of the gearbox.  
         [0015]    The shaft as well as the supporting tube are divided, whereby bevel gears are disposed on those shaft ends that face the gearbox; the bevel gears connect the shaft sections with one another in a torque transferring manner. In this connection, the shaft ends are held and guided in the shafts of the gearbox with one or more bearing means, preferably double rowed, grooved ball bearings. All known types of miter gears, for example bevel gearings or cogwheel gearings, can be used, whereby it is expedient to differentiate the speeds of the two shaft sections relative to one another. A ratio of 1.9 to 2.1, transferred into slow or fast, has been shown to be advantageous when working with a pole pruner. In this connection, a pole pruner has a saw chain to that circulates about a guide bar, or has an oscillating saw blade, and serves for the removal of branches or underbrush from locations in trees or bushes that could otherwise be reached only with the aid of auxiliary means.  
         [0016]    Pursuant to one preferred embodiment of the inventive manually guided implement, the shaft ends of the shaft sections are fixedly and axially removably connected with respective hubs in the gearbox. The hubs are held and guided in the gearbox or in the shafts via a bearing means. It could also be expedient to monolithically form the hubs with a respective bevel gear.  
         [0017]    For the positive and/or frictional clamping connection of the supporting tube sections with the gearbox, each shaft is provided with one or more elongated slots and with a clamping device. The supporting tube sections are thereby releasably and rotatably held in the shafts. As a consequence of the structural features, the coordination of the supporting tube sections relative to the shafts, in other words to the drive and driven sides of the gearbox, can be varied. As a result, the speed ratio can be adjusted to slow or fast by means of a simple interchange.  
         [0018]    It is expedient to embody the housing portions as castings, die cast parts, or injection molded parts, and to screw or bolt them to one another. With a pole pruner, it has been shown that the angle of the supporting tube sections, especially their longitudinal axes, relative to one another is advantageously approximately 150°.  
         [0019]    Further specific features of the present invention will be described in detail subsequently.  
       DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0020]    Referring now to the drawings in detail, the manually-guided implement  1  illustrated in FIG. 1 serves for the removal of branches, trees or the like, and is also designated as a pole pruner  2 . The implement  1  comprises a supporting tube  4 , on one end  3  of which is fixed a drive motor  5 , and on the other end  6  of which is fixed a working tool  7 . In the illustrated embodiment, the supporting tube  4  is formed as a telescopic rod  33 , and comprises an outer tube  34  and an inner tube  35  that is longitudinally displaceable within the outer tube. The working tool  7  is driven with the aid of a shaft  8  that extends in the supporting tube  4  and connects the drive motor  5  and the tool  7 . In this connection, the working tool  7  is essentially formed of a guide bar  36  about the periphery of which circulates a saw chain  37 .  
         [0021]    The supporting tube  4  is composed of a first section  9  that is associated with the drive means  5 , and a second section  10  that is associated with the tool  7 ; the sections  9 , 10  are fixedly interconnected by a gearbox  11  of a miter gear  12  so that they do not bend or rotate relative to one another. In this connection, the sections  9  and  10  of the supporting tube  4  are rigidly interconnected at an angle  13  of about 150°. In the illustrated embodiment, the axial ends  14 , 15  of the supporting tube sections  9 , 10 , which ends are remote from the drive motor  5  and the working tool  7  respectively, extend into cylindrical shafts  16 , 17  on the gearbox  11 . It can also be expedient to embody one of the two supporting tube sections  9 , 10  monolithically, for example as a casting, with a gearbox  11 . In the embodiment illustrated in FIGS.  1  to  6 , the shafts  16 , 17  are monolithically formed with the spherical gearbox  11 .  
         [0022]    To simplify the manufacture of the gearbox with the shafts, in the embodiment illustrated in FIGS.  1  to  6  the gearbox  11  and the shafts  16 , 17  are formed of two housing portions  18 , 19  that have the same shape and that are symmetrical relative to one another along a centerline  20  of the housing (see FIGS. 2 and 3). The shaft  8  between the drive motor and the working tool is interrupted in the gearbox  11 , especially in the region of the respective shaft bases  38 , 39  at the gearbox. In the embodiment shown in FIGS. 2 and 3, the shaft  8  ends in the region of the respective axial ends  40  and  41  of the shafts  16  and  17  that face away from the gearbox  11 . Not only on the shaft ends  25 , 26  that face the gearbox  11 , but also on the shaft ends  46  and  47  in the region of the axial ends  40  and  41 , the shaft sections  21 , 22  have a polygonal portion, in the illustrated embodiment a square end. Disposed in the gearbox  11 , on the shaft ends  25 , 26 , are bevel gears  23 , 24  that are fixedly connected with the shaft ends and the axes of which intersect in the interior of the gearbox  11 . A flexible shaft, a universal coupling or the like can also be provided. The bevel gears  23 , 24  are monolithically formed with hubs  29 , 30  that extend axially from the interior of the gearbox  11  into the respective shaft base  38 ,  39  of the shafts  16 , 17 . Each of the hubs  29 , 30  extends through a bearing means  27 , 28 , whereby in the illustrated embodiment the bearing means  27 , 28  are embodied as double rowed, grooved ball bearings. The grooved ball bearings are supported against the inner wall of the shaft bases  38 , 39 . In this way, a miter gear  12  is formed that can be inserted in a modular fashion between the carrying tube sections  9  and  10 . The speed of the shaft sections  21 ,  22  is differentiated by the miter gear  12 , and in the illustrated embodiment is transmitted in the ratio of 1.9 to 2.1.  
         [0023]    As can be seen in FIG. 2, each shaft  16 , 17  has at least one elongated slot  31 , 32 . In the illustrated embodiment, each shaft  16 , 17  is respectively provided with an elongated slot  31 , 31 ′ and an elongated slot  32 , 32 ′ that are disposed across from one another on the shafts. The elongated slots extend axially approximately from the ends  40 , 41  over half of the axial length of the respective shaft  16 , 17 , and extend through the wall  42  thereof. For the mutual screwing or bolting together of the housing portions  18 , 19 , in the region of the axial ends  40 , 41  of the shafts  16 , 17 , and in the region of the shaft bases  38 , 39 , cylindrical socket-shaped mounting means,  43 , 43 ′ and  44 , 44 ′, which extend tangentially relative to the wall  42  and transverse to the centerline  20  of the housing, are monolithically formed on the respective housing portions  18 , 19 . In this connection, in the axial direction, the mounting means  43 , 43 ′ and  44 , 44 ′ are disposed across from one another and in alignment on the housing portions  18 , 19 . The mounting means  43 , 43 ′ and  44 , 44 ′ serve for the positive and/or frictional receipt of securing elements. In the embodiment illustrated in FIGS.  1  to  6 , the securing elements are embodied as screws or bolts, especially cylindrical bolts, that extend through the mounting means  43 , 43 ′ and have threads that engage the mounting means  44 , 44 ′. This results in a detachable clamping connection between the shafts  16 , 17  and the ends  14 , 15  of the supporting tube sections  9 , 10  when the supporting tube sections appropriately extend into the shafts. As a function of the exchangeable arrangement of the supporting tube sections  9 , 10  relative to the shafts  16 , 17 —an installation position of the miter gear  12  rotated by 180°—the speed ratio of the miter gear can thereby be defined from slow to fast or from fast to slow.  
         [0024]    For an economical manufacture of the gearbox  11 , the latter is formed as a casting, a die cast part, or as an injection molding of lightweight metal or thermoplastic polymeric material, especially fiber-reinforced thermoplastic material. Instead of the illustrated clamping connection, it is also possible to use holding clamps that span the shaft ends  40 , 41 .  
         [0025]    FIGS.  4  to  6  show, by way of example only, various possible positions of the working tool  7  relative to the supporting tube section  9 . In contrast to a starting position shown in FIG. 4, in FIG. 5 the working tool  7 , together with the gearbox  11 , are rotated about the supporting tube section  9  that is on the motor side. For this purpose, the clamping connection between the supporting tube section  9  and the shaft  16  is loosened or released, the gearbox  11  together with the working tool  7  are rotated about the supporting tube section  9  that is on the motor side, and subsequently the clamping connection is again established. A further adjustment possibility is provided in the region of the shaft  17  that is on the tool side. The relative adjustment of the working tool from the position shown in FIG. 5 into the position shown in FIG. 6 can be achieved by releasing the clamping of the supporting tube section  10  in the shaft  17 , rotating the working tool relative to the gearbox  11 , and subsequently again establishing the clamping between the shaft  17  and the supporting tube section  10 .  
         [0026]    The miter gear  12  can also divide the supporting tube, or in the region of the drive motor can form the connection between the drive means and the supporting tube. In addition, as illustrated, the tool head is to be connected to the supporting tube via the miter gear. Depending upon need, a plurality of miter gears having the same or different angles can also be disposed over the length of the supporting tube.  
         [0027]    The specification incorporates by reference the disclosure of German priority document 201 10 321.4 filed Jun. 21, 2001.  
         [0028]    The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.

Technology Category: 1