Abstract:
The invention is based on a hand power tool, in particular a drilling or chipping hammer, comprising a striking mechanism having a drive end bearing ( 12, 58 ) that is turnably supported on an intermediate shaft ( 10 ), via which a piston ( 14 ) is capable of being driven in reciprocating fashion in the axial direction.  
     It is proposed that the drive end bearing ( 12 ) is supported by a radial bearing ( 16 ) in at least one axial direction via the intermediate shaft ( 10 ).

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention is based on a hand power tool, in particular a drilling and/or chipping hammer, according to the preamble of claim 1.  
           [0002]    A drilling and chipping hammer having a striking mechanism that comprises a drive end bearing is generally known. The drive end bearing comprises a structure that is turnably supported on an intermediate shaft, which said structure comprises a ground-in ball track in its radially outer region, which said ball track is located in a plane that is tilted in the axial direction of the intermediate shaft. The structure is capable of being driven in rotating fashion via a separable clutch.  
           [0003]    A functional unit of the drive end bearing is situated on the structure with an annular bearing seat and a bolt, which said functional unit is turnably interconnected with the structure via balls guided in the ball track. The bolt of the functional unit is displaceably supported in a cross hole of a pivotably supported cross bolt of a piston of the striking mechanism and, as a result of this, is interconnected with the piston in driving fashion.  
           [0004]    If the drilling and chipping hammer is operated in the striking mode, the structure is driven in rotating fashion, and the bolt of the functional unit and the piston are moved in reciprocating fashion in the axial direction, which produces an alternating axial load on the drive end bearing. A ball track of a grooved ball bearing is ground in a radially outer region in the structure of the drive end bearing on a side furthest from a tool mount, via which said grooved ball bearing the drive end bearing is fixed in position in both axial directions in a housing of the drilling and chipping hammer.  
         ADVANTAGES OF THE INVENTION  
         [0005]    The invention is based on a hand power tool, in particular a drilling and/or chipping hammer, comprising a striking mechanism having a drive end bearing turnably supported on an intermediate shaft, via which said drive end bearing a piston is capable of being driven in reciprocating fashion in the axial direction.  
           [0006]    It is proposed that the drive end bearing be supported by a radial bearing in at least one axial direction via the intermediate shaft. An exact positioning of the drive end bearing on the intermediate shaft can be obtained, and the drive end bearing can be pre-mounted on the intermediate shaft using simple design means, and it can be installed—mounted on the intermediate shaft—in the hand power tool. If the drive end bearing is supported by a radial bearing that can absorb axial forces in two directions, additional components and space can be saved in particular.  
           [0007]    Space can be further saved by locating the radial bearing in an inner region of a structure of the drive end bearing, and particularly so when a space containing the radial bearing overlaps a space containing a functional unit of the drive end bearing in the axial direction.  
           [0008]    The radial bearing can be formed, basically, by a sliding bearing. If the radial bearing is formed by a rolling bearing, however, a competitively-priced component can be used that has minimal friction due to the fact that rolling elements roll around, and an advantageous no-load characteristic of the drive end bearing can be obtained.  
           [0009]    In a further embodiment of the invention it is proposed that the radial bearing be mounted on the intermediate shaft by means of a press fit. The drive end bearing is capable of being supported in the axial direction on the intermediate shaft using simple design means via the press fit. The radial bearing can also be interconnected with the intermediate shaft via other connections having non-positive, positive and/or bonded engagement appearing reasonable to one skilled in the art, e.g., via a circlip, a ball track ground in the intermediate shaft, a non-positive retainer, etc.  
           [0010]    It is further proposed that the intermediate shaft and/or the drive end bearing form a part of the radial bearing, in fact by the fact that a ball track is ground in the intermediate shaft and/or in the drive end bearing and/or the structure of the drive end bearing. Additional components, space, weight, assembly expenditure and costs can be saved.  
           [0011]    Particularly advantageously, arising axial forces are capable of being transmitted in at least one direction via the radial bearing to at least one component mounted on the intermediate shaft. A design can be obtained with which the axial forces—compression forces, in particular—can be supported particularly advantageously via the adjacent component on the intermediate shaft and via the intermediate shaft in a housing. As a result, the mounting of the radial bearing itself can be advantageously designed to absorb the forces in one axial direction, which are not as great. If the radial bearing is mounted on the intermediate shaft with non-positive engagement via a press fit, said radial bearing can be pressed onto the intermediate shaft with minimal deformation, and small tolerances can be achieved.  
           [0012]    The component that is located on the intermediate shaft and absorbs axial forces can be formed by a retainer mounted on the intermediate shaft with positive, non-positive and/or bonded engagement, or by another component appearing reasonable to one skilled in the art. If the rolling bearing is located on a side of the drive end bearing furthest away from a tool mount, an advantageous utilization of space can be achieved and, in particular, a component that is already present—a gear, in particular—can be used for additional axial support using simple design means, and additional components can be saved.  
       
    
    
     SUMMARY OF THE DRAWINGS  
       [0013]    Further advantages result from the following description of the drawings. Exemplary embodiments of the invention are presented in the drawings. The drawings, the description, and the claims contain numerous features in combination. One skilled in the art will advantageously consider them individually as well and combine them into reasonable further combinations.  
         [0014]    [0014]FIG. 1 is a schematic illustration of a drilling and chipping hammer,  
         [0015]    [0015]FIG. 2 is an enlarged section II in FIG. 1, and  
         [0016]    [0016]FIG. 3 is a variant of FIG. 2. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    [0017]FIG. 1 is a schematic illustration of a drilling and chipping hammer having a not-shown electric motor in a housing  42 , as well as a gearbox and a striking mechanism. A first handle  50  extending at a right angle to the operating direction  48  is mounted on the housing  42  behind the tool mount  44  against an operating direction  48 . A second, U-shaped handle  52  extending at a right angle to the operating direction  48  is located on the side of the housing  42  furthest from the tool  46 , which said handle is interconnected with the housing  42  at its first end furthest from a tool axis via a hinge joint  54  having a pivot axis extending transversely to the operating direction  48 . At its second end, the handle  52  is interconnected with the housing  42  via a vibration-isolating device.  
         [0018]    The electric motor has a drive shaft on which a pinion is integrally molded. The pinion meshes with a spur gear  22  that is situated in torsion-resistant fashion on an intermediate shaft  10  on a side furthest from a tool mount  44  (FIG. 2). By means of the intermediate shaft  10 , a drill bit  46  held in the tool mount  44  is capable of being driven in striking fashion via the striking mechanism, and in rotating fashion via a work spindle  68  designed as hollow shaft.  
         [0019]    A drive end bearing  12  is located on a side of the spur gear  22  closest to the tool mount  44 , which said drive end bearing comprises a structure  72  that is situated on the intermediate shaft  10  in a manner that allows it to rotate via a needle bearing  70 . The structure  72  comprises an integrally-molded, turnably driving tooth system  24  on its end face closest to the tool mount  44 . A collar  32  extending in the axial direction is integrally molded on the structure  72  on an end face furthest from the tool mount  44 , in the radially inner region  18  of which said collar a radial bearing  16  designed as grooved ball bearing is located. The collar  32  forms a part of the radial bearing  16 , the rolling elements  28 —designed as balls—of which roll radially outwardly around in a ball track  26  ground in a radially inwardly-facing side of the collar  32 . Radially inwardly, the rolling elements  28  roll around in a bearing inner race  30  of the radial bearing  16 .  
         [0020]    The bearing inner race  30  mounted on the intermediate shaft  10  with non-positive engagement in the axial direction by means of a press fit bears against the spur gear  22  with its side  36  furthest from the tool mount  44 , which said spur gear is also mounted on the intermediate shaft  10  by means of a press fit. The bearing inner race  30  and the spur gear  22  are pressed onto the intermediate shaft  10  in the same process step.  
         [0021]    In its radially outer region, the structure  72  comprises a ground-in ball track  34  that is located in a plane that is tilted in the axial direction of the intermediate shaft  10 . A functional unit  20  with an annular bearing seat and a bolt  40  is located on the structure  72 , which said functional unit is turnably interconnected with the structure  72  via balls  38  guided in the ball track  34 , whereby a space containing the radial bearing  16  and a space containing the functional unit  20  overlap in the axial direction. The bolt  40  of the functional unit  20  is displaceably supported in a cross hole of a pivotably supported cross bolt  56  of a piston  14 . If the structure  72  is driven in rotating fashion via the turnably driving tooth system  24  within the functional unit  20  that is standing still in the direction of rotation, the bolt  40  of the functional unit  20  executes a reciprocating motion and drives the piston  14  in reciprocating fashion in the axial direction.  
         [0022]    If the piston  14  is moved in the direction away from the tool mount  44  via the bolt  40  of the functional unit  20  of the drive end bearing  12 , an air cushion located in the work spindle  68  is expanded, whereby the drive end bearing  12  is braced, via its structure  72 , in the direction toward the tool mount  44  via the bearing inner race  30  of the radial bearing  16  and via the intermediate shaft  10  in the housing  42 . The press fit of the bearing inner race  30  is designed to withstand a first bracing force that occurs under these circumstances.  
         [0023]    If the piston  14  is moved via the bolt  40  of the functional unit  20  of the drive end bearing  12  in the direction toward the tool mount  44 , an air cushion located in the work spindle  68  is compressed, whereby the drive end bearing  12  is braced, via its structure  72 , in the direction away from the tool mount  44  via the bearing inner race  30  of the radial bearing  16 , the spur gear  22  on the intermediate shaft  10 , and via the intermediate shaft  10  in the housing  42 . A second bracing force—that is greater than the first bracing force—generated as a result is transmitted to the intermediate shaft  10  by means of the press fits of the bearing inner race  30  and the spur gear  22 , the effects of which complement each other.  
         [0024]    [0024]FIG. 3 shows a section of an alternative drilling and chipping hammer having a drive end bearing  58 . Components that essentially remain the same are basically labelled with the same reference numerals. Moreover, the description of the exemplary embodiment shown in FIGS. 1 and 2 can be referred to with regard for features and functions that remain the same. The following description is essentially limited to the differences from the exemplary embodiment shown in FIGS. 1 and 2.  
         [0025]    On its side closest to the tool mount  44 , a structure  74  of the drive end bearing  58  comprises radial holes  62  in an anterior region in which turnably driving balls  64  are located. The turnably driving balls  64  are enclosed radially by an annular spring  66  that loads the turnably driving balls  64  radially inwardly. During a coupling process, the turnably driving balls  64  correspond with recesses in a not-shown turnably driving element situated in torsion-resistant fashion on an intermediate shaft, and a purposeful build-up of torque can be achieved.  
       REFERENCE NUMERALS  
       [0026]    [0026] 10  Intermediate shaft  
         [0027]    [0027] 12  Drive end bearing  
         [0028]    [0028] 14  Piston  
         [0029]    [0029] 16  Radial bearing  
         [0030]    [0030] 18  Radial Region  
         [0031]    [0031] 20  Functional unit  
         [0032]    [0032] 22  Component  
         [0033]    [0033] 24  Turnably driving tooth system  
         [0034]    [0034] 26  Ball track  
         [0035]    [0035] 28  Rolling element  
         [0036]    [0036] 30  Bearing inner race  
         [0037]    [0037] 32  Collar  
         [0038]    [0038] 34  Ball track  
         [0039]    [0039] 36  Side  
         [0040]    [0040] 38  Ball  
         [0041]    [0041] 40  Bolt  
         [0042]    [0042] 42  Housing  
         [0043]    [0043] 44  Tool mount  
         [0044]    [0044] 46  Tool  
         [0045]    [0045] 48  Operating direction  
         [0046]    [0046] 50  Handle  
         [0047]    [0047] 52  Handle  
         [0048]    [0048] 54  Hinged joint  
         [0049]    [0049] 56  Cross bolt  
         [0050]    [0050] 58  Drive end bearing  
         [0051]    [0051] 60  Region  
         [0052]    [0052] 62  Radial hole  
         [0053]    [0053] 64  Turnably driving ball  
         [0054]    [0054] 66  Annular spring  
         [0055]    [0055] 68  Work spindle  
         [0056]    [0056] 70  Needle bearing  
         [0057]    [0057] 72  Structure  
         [0058]    [0058] 74  Structure