Hammer drill with wobble mechanism and hollow drive shaft

A hand power tool has a housing, a drive motor and a gear mechanism arranged in the housing. A tool receptacle accommodates a tool, and a gear wheel drives a rotary sleeve in rotation from the drive motor and the gear mechanism and thereby the tool receptacle. A hammering mechanism is located inside the rotary sleeve and drivable translationally via a wobble gear. The gear mechanism has a driving gear wheel meshing with a motor pinion and arranged on a shaft by which the wobble gear mechanism is drivable to revolve. The shaft is configured as a hollow shaft on which the driving gear wheel is retained nondisplaceably and in a manner fixed against rotation. The wobble gear mechanism is located adjacent to the driving gear wheel on the shaft rotatably and couplably to the hollow shaft.

The invention described and claimed hereinbelow is also described in DE 102004026845.2, filed Jun. 2, 2004. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119 (a)-(d).

BACKGROUND OF THE INVENTION

The invention is based on a hand power tool, in particular a drilling hammer and/or jackhammer.

Known hand power tools of this type have an L-shaped construction, in which the gear mechanism is embodied as a single-stage cone wheel gear, and the drive mechanism of the hammering mechanism is embodied as a wobble gear mechanism. Both the driving gear wheel embodied as a cone wheel and the wobble gear mechanism are located on one shaft, which makes for a space-saving, compact mode of construction. A disadvantage of such hand power tools, however, is that in terms of their functions they are limited to two functions, namely hammer drilling and chiseling. A different hand power tool of a similar kind likewise makes only two functions possible, specifically hammer drilling and drilling.

On the other hand, hand power tools in the form of so-called combination devices, also of L-shaped construction, are also known in which the hammering mechanism is likewise drivable via a wobble gear mechanism; these hand power tools have a two-stage gear mechanism construction. Such hand power tools, as combination devices, make three functions possible, namely drilling, hammer drilling, and chiseling. However, these hand power tools have the disadvantage of a complicated, expensive construction with a large number of components, because of the individual gear and bearing stages, and therefore have the disadvantage of reduced efficiency. Moreover, these hand power tools have a relatively high weight, and because of the internal space required also have correspondingly large dimensions and are therefore not as handy as is desired.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a hand power tool which eliminates the disadvantages of the prior art.

In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a hand power tool, comprising a housing; a drive motor and a gear mechanism arranged in said housing; a tool receptacle in which a tool is guidable; a gear wheel via which a rotary sleeve is driven in rotation from said drive motor and said gear mechanism and thereby said tool receptacle is driven in rotation; a hammering mechanism located inside said rotary sleeve and drivable translationally via a wobble gear, said gear mechanism having a driving gear wheel meshing with a motor pinion and arranged on a shaft by which said wobble gear mechanism is drivable to revolve, said shaft being configured as a hollow shaft on which said driving gear wheel is retained nondisplaceably and in a manner fixed against rotation, said wobble gear mechanism being located adjacent to said driving gear wheel on said shaft rotatably and couplably to said hollow shaft.

The hand power tool according to the invention has the following advantages over the prior art: In itself, the hand power tool combines a merely one-stage gear mechanism, with the consequence of a space-saving, compact, lightweight construction, as well as its design as a combination tool, which makes all functions possible, that is, at least drilling, hammer drilling and chiseling.

A reduction in the number of gear and bearing stages and thus in the number of necessary components is achieved. Bundling the functions together leads to a design that is shorter by about 30 mm, for instance, with at the same time an insignificant increase in the dimensions in height. The reduction in gear and bearing stages increases the efficiency. An overall economy of material and expense is achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, a detail of interest here is schematically shown of a hand power tool10which is embodied in particular as a drilling hammer and/or jackhammer. The hand power tool10has a housing11, which includes a gearbox12, a bearing flange13, and a hammering mechanism housing55. The housing11includes an approximately vertically oriented, in particular electrical, drive motor that is not otherwise visible and that via a gear mechanism14acts on a downstream drilling and/or hammering mechanism. The gear mechanism14has a motor pinion15, embodied in particular as a conical pinion with an approximately vertical axial course in terms of the drawing.

The motor pinion15is driven by the drive motor, not shown, and meshes with a driving gear wheel16, which is embodied in particular as a cone wheel. The driving gear wheel16is retained axially nondisplaceably and in a manner fixed against relative rotation on a shaft17. Via the shaft17and a gear wheel18, in particular a spur wheel, a rotary sleeve19, which can also be called a drilling shaft, is driven to rotate. The gear wheel18is coupled in the circumferential direction with the rotary sleeve19in a way that transmits torque, and between it and the rotary sleeve19, there may also be a safety coupling, not further shown. Via the gear wheel18and the rotary sleeve19, a tool receptacle, not further shown, in which a tool can be guided, can be driven to rotate.

By means of the gear mechanism14, specifically the motor pinion15, the driving gear wheel16, and the shaft17, a hammering mechanism21can be driven translationally via a wobble gear mechanism20; the hammering mechanism is located here inside the rotary sleeve19and is embodied in particular as an air cushion hammering mechanism. The hammering mechanism21has a drive piston22that is movable back and forth and acts upon a beater24via an air cushion23. In the exemplary embodiment shown, the drive piston22is embodied as a hollow piston, which is guided displaceably inside the rotary sleeve19and which in its interior contains the beater24. This part24, called a beater, may instead be a further piston, in which case a beater then adjoins it farther to the left in the drawing.

The tool not shown is received in the tool receptacle in such a way that upon being driven to rotate it is slaved in the circumferential direction and is movable back and forth in the tool receptacle on being driven via the hammering mechanism21and is acted upon with the percussion energy by the beater in a way that is usual in such drilling hammer and/or jackhammers. The cylindrical wall of the hollow drive piston22is identified by reference numeral25and represents a guide tube for the beater24or a corresponding piston. On the outer end of the drive piston22, a rotary bolt26with a transverse bore27is retained in a fork28.

The wobble gear mechanism20has a wobble body29, which has an annular groove31extending obliquely to the longitudinal center axis30; a ring33is rotatably supported on this annular groove via balls32. The ring33has a slaving bolt34, which extends inside the diagonal plane35and is received with play in the transverse bore27of the rotary bolt26. Upon a revolving driving motion of the wobble body29, the ring33wobbles back and forth with the slaving bolt34between the position shown in dashed lines and the position shown in solid lines, and as a result the drive piston22is driven axially back and forth.

In a special feature, the shaft17is embodied as a hollow shaft36, on which the driving gear wheel16is retained nondisplaceably and in a manner fixed against relative rotation; the driving gear wheel can be press-fitted onto the hollow shaft. The wobble gear mechanism20with the wobble body29is also rotatable on the hollow shaft36, adjacent to the driving gear wheel16, and in such a way that it can be coupled to the hollow shaft36.

The hollow shaft36is rotatably supported on both ends by means of bearings in the housing11, specifically by means of a fixed bearing37, for instance in the form of a ball bearing, on one end and by means of a loose bearing38, for instance in the form of a needle bearing, on the other. The fixed bearing37is received in the bearing flange13. The loose bearing38is retained in the gearbox12.

On an approximately middle axial portion, the hollow shaft36has a plurality of radially passable oblong slots39, distributed over the circumferential direction, each of which contains a transmission element40, which for instance comprises a roller, in particular a cylindrical body, or instead a ball or the like. The transmission elements40protrude radially outward past the outer circumferential face41of the hollow shaft36and can thereby enter into engagement with the wobble gear mechanism20, in particular the wobble body29, as a result of which the wobble gear mechanism20is couplable with the hollow shaft36for rotary slaving.

The wobble body29, on its inner circumferential face42, has a plurality of longitudinal recesses43, such as longitudinal grooves, which can be engaged on the inside by the transmission elements40by axial motion as shown inFIGS. 2 through 4. The longitudinal recesses43are interrupted, for example approximately in the region of the middle, by an encompassing groove44, in which the transmission elements40can revolve freely without a form-locking connection with the wobble body29. This function position is shown inFIG. 1, in which the transmission elements40, with the region protruding past the outer circumferential face41, engage the inside of the encompassing groove44but not the longitudinal recesses43.

A switching shaft45is supported axially displaceably and received freely movably inside the hollow shaft36. Axially displacing the switching shaft45makes it possible to set all the operating modes of the hand power tool10, that is, drilling, hammer-drilling, vario-lock, and chiseling, as is shown inFIGS. 1 through 4in different axial positions of the switching shaft45. On its outer circumferential face46, the switching shaft45has an encompassing recess47, in particular an encompassing groove, whose axial width is for instance approximately equal to that of the transmission elements40.

The transmission elements40, protruding radially inward past the hollow shaft36, engage the inside of this recess47, in particular the encompassing groove, in a form-locking manner and remain in form-locking engagement with this recess47in every displaced position of the switching shaft45. The switching shaft45is thus axially displaceable, together with the transmission elements40engaging the recess47, relative to the hollow shaft36and the wobble gear mechanism20, in particular the wobble body29, thereon between positions in which the transmission elements40engage the longitudinal recesses43, in particular longitudinal grooves, of the wobble body29in a form-locking manner for its rotary slaving (FIGS. 2 through 4), and a position shown inFIG. 1, in which the transmission elements40can engage the encompassing groove44of the wobble body29and roll along therein.

The switching shaft45has an actuating portion48, located on the right in the drawings, with a stop disk49and on the other end has an end portion50, which is provided with an external toothing51, for instance with longitudinally oriented teeth, and in particular with a spline shaft toothing. The actuating portion48, in particular the stop disk49, is engaged by an actuating device52for axial displacement of the switching shaft45. The toothing51on the end portion50is embodied as a spur toothing and meshes, in the various relative axial displacement positions of the switching shaft45, with the gear wheel18, in particular the spur wheel, of the rotary sleeve19.

In an end region53that is associated with the end portion50of the switching shaft45that has the toothing51, the hollow shaft36has a slaving part54, for instance an internal toothing, that is axially aligned with the toothing51of the switching shaft45. The toothing51of the switching shaft45in form-locking engagement with this slaving part54in a plurality of axial displacement positions, which correspond to the functions of drilling and hammer drilling. In the axial displacement position of the switching shaft45that corresponds to the vario-lock or chiseling function (FIG. 3andFIG. 4, respectively), the toothed slaving part54of the hollow shaft36is conversely not in form-locking engagement with the toothing51of the switching shaft45; seeFIGS. 3 and 4. The slaving part54, in particular the internal toothing, of the hollow shaft36, being merely a slaving toothing, does not make stringent demands in terms of quality and can therefore be manufactured economically by non-metal-cutting shaping, such as rolling, pressing, or the like. This is favorable for the sake of an economical mode of construction.

The housing11, in particular its hammering mechanism housing55, has a blocking part56axially aligned with the toothing51of the end portion50of the switching shaft45, such as an internally-toothed hollow wheel part integral with it. Upon displacement of the switching shaft45into the function position for chiseling (FIG. 4), the switching shaft, with its toothing51, can be brought axially into blocking engagement with the toothing of the blocking part56.

The wobble gear mechanism20, in particular the wobble body29, is supported with a clearance fit directly on the outer circumferential face41of the hollow shaft36and thereby retained axially nondisplaceably between the driving gear wheel16on the one hand and the housing11, in particular the gearbox12, on the other. When the hammering mechanism21is operative, involving hammering mechanism forces that act primarily axially rearward, these forces are diverted directly via the fixed bearing37of the hollow shaft36into the bearing flange13and from there onward into the gearbox12.

The actuating device52is located on the back end of the hand power tool10. On the housing11, for instance on the bearing flange13, it has a rotary actuator57, in particular a selector wheel, which is coaxial to the switching shaft45and can be rotated about the longitudinal center axis30into various positions. The latching and holding of the rotary actuator57in the particular desired switching position can be implemented for instance by means of a hexagonal profiling of the rotary actuator57in combination with a leaf spring58. Still other possibilities for doing this are within the scope of the invention.

Another component of the actuating device52is a switching member59, which is axially displaceable by means of the rotary actuator57and is embodied for instance as a switching bell. The switching member59activates the actuating portion48, in particular the stop disk49, of the switching shaft45for axially displacing the switching shaft. The switching member59is axially pressed against the rotary actuator57by a compression spring60. The compression spring60is supported on one end on the bearing flange13and on the other on the switching member59.

The switching member59is thus axially displaceable to the left inFIG. 1, counter to the action of an axial restoring force generated by the compression spring60. The switching member59is penetrated by a bolt61of the actuating portion48, whose stop disk49, forming a slaving means, rests on a bottom face62of the switching member59that is pressed axially to the right inFIG. 1against the stop disk49via the compression spring60. Upon the rotary actuation of the rotary actuator57, the switching member59is displaceable to the left, beginning at51, relative to the actuating portion48, counter to the action of the compression spring60.

Between the switching member59and the switching shaft45, there is also an axial compression spring63, which acts as a synchronizing spring. If beginning at the position shown inFIG. 1the switching member59is displaced axially to the left by rotary actuation of the rotary actuator57, counter to the action of the compression springs60and63.

If despite the action of the compression spring63the switching shaft45remains in the position because the transmission elements40do not immediately axially engage the inside of the longitudinal recesses43of the wobble body29, or the toothing51of the switching shaft45for instance does not move axially into the blocking part56, in particular the internally-toothed hollow wheel part, of the hammering mechanism housing55, then the compression spring63is prestressed between the switching member59and the switching shaft45. Once the synchronization takes place after that, the compression spring63causes an axial displacement of the switching shaft45, far enough that the transmission elements40axially engage the longitudinal recesses43, or the toothing51engages the blocking part56, and in the process causes the stop disk49to strike the bottom face62.

The rotary actuator57, in particular the selector wheel, of the actuating device52has an obliquely extending end face64, which is preferably provided with a groovelike indentation65that is open toward the left in terms ofFIG. 1. The switching member59has a lug66, which engages the indentation65and is held in this engaged position in the indentation65by the action of the compression spring60. The switching member59is guided nonrotatably, but axially displaceably, in the housing11, for instance in the bearing flange13, for instance by means of a longitudinal slit in the bearing flange13which is engaged in a form-locking manner by a part of the switching member59. Rotating the rotary actuator57can impose an axial motion on the switching member59, whereupon the rotary actuator57can be rotated continuously in an arbitrary direction without an end stop. Slaved rotation of the switching member59is prevented in the process. Depending on the direction of motion of the switching member59, the axial displacement is transmitted, either via the stop disk49or via the compression spring63acting as a synchronizing spring, to the switching shaft45and to the transmission elements40that engage the encompassing recess47.

If a bidirectional motion is realized in the hand power tool10by means of a function part, not shown, in particular a rotatable brush plate, that makes this motion possible, then it may be advantageous if the counterclockwise travel can be switched on only in the drilling position shown inFIG. 1, but not in the hammer drilling position ofFIG. 2or the chiseling position ofFIG. 4. The preclusion of counterclockwise travel in these positions makes it possible to design and optimize the fan of the drive motor in one direction of rotation. In that case, incorrect use in the hammer-drilling mode (FIG. 2) is furthermore precluded. To that end, an arresting member67, such as an arresting bar, is assigned to the rotary actuator57and meshes with an outer cam path68of the rotary actuator57and is actuatable by the rotary actuator57in the rotary positions that correspond to the hammer-drilling mode and the chiseling-drilling mode, in such a way that a blockage of rotation of the rotatable function part, in particular a rotatable brush plate, is brought about.

In the functional position of the switching shaft45as shown inFIG. 1, only a rotational drive of the rotary sleeve19and via it of the tool receptacle and of the tool is effected. The hand power tool10is in the drilling mode of operation. The rotational drive exerted by the motor pinion15on the driving gear wheel16and the hollow shaft36connected to it in a manner fixed against relative rotation is transmitted by the hollow shaft36, via its slaving part54in the form of the internal toothing, the toothing51of the switching shaft45, and the gear wheel18meshing with it, to this gear wheel and to the rotary sleeve19, which is as a result driven to rotate. The transmission elements40are not in engagement with the longitudinal recesses43of the wobble body29. Although upon revolution of the hollow shaft36the transmission elements40are slaved to the hollow shaft, nevertheless for the lack of form locking between the transmission elements40and the wobble body29, the hammering mechanism21is not in operation. The transmission elements40, for instance slaving rollers, rotate without loading in the encompassing groove44of the fixed wobble body29.

InFIG. 2, the switching shaft45is in a position displaced to the left compared toFIG. 1, and in this position the transmission elements40revolving by means of the hollow shaft36are moved outward axially into the longitudinal recesses43, in particular longitudinal grooves, of the wobble body29. Because the hollow shaft36is driven to rotate, the wobble body29is driven to revolve by its form lock with it. The hammering mechanism21is thus activated. Since moreover the hollow shaft36, with its internally toothed slaving part54, continues to be in engagement with the toothing51, and the gear wheel18is meshing with the latter toothing, the gear wheel18and the rotary sleeve19are also driven to revolve because of the rotational drive of the hollow shaft36via the toothing51. The tool, not shown, is thus driven to rotate at the same time. The function position here is hammer drilling.

The position shown inFIG. 3, in which the switching shaft45is displaced still farther to the left compared toFIG. 2, is the vario-lock function position. In this position, the tool, together with the rotary sleeve19and the gear wheel18, can be rotated into a desired working position without the expenditure of force; this is because the hollow shaft36, with its internally toothed slaving part54, is axially out of engagement with the toothing51of the switching shaft45, which is thus rotatable from the tool upon rotary actuation of the rotary sleeve19and the gear wheel18. The transmission elements40continue to be in engagement with the longitudinal recesses43, in particular longitudinal grooves, of the wobble body29.

In the function position ofFIG. 4, the switching shaft45is displaced all the way to the right axially, into the position in which its toothing51meshes in a form-locking manner with the internally toothed blocking part56of the hammering mechanism housing55, and as a result the switching shaft45is prevented from rotating. Since the internally toothed slaving part54of the hollow shaft36is not in engagement with the toothing51of the switching shaft45, the driven hollow shaft36can revolve relative to the nonrotatably fixed switching shaft45; the slaved transmission elements40slave the wobble body29in the direction of revolution, since the transmission elements40are in form-locking engagement, in this axial position as well, with the longitudinal recesses43, in particular longitudinal grooves, of the wobble body29.

The hand power tool10described, in terms of its gear mechanism14, requires only a single-stage cone wheel gear with the motor pinion15and the driving gear wheel16. The hand power tool10makes all the functions of drilling, hammer drilling, vario-lock and chiseling possible. The hand power tool10is compact in structure and economical. The number of components and gear stages is reduced to a small amount. With this design of the hand power tool10, a shorter construction, for instance about 30 mm shorter, is possible, while any slight increase in height is insignificant.