In the exploded view of
An electric motor 10 (shown schematically) includes an armature shaft 12, on which a gear wheel, serving as a drive pinion 31, is located, in a manner fixed against relative rotation. The drive pinion 31 forms one part of a two-stage planetary gear 30 and drives planet wheels 32 with the first gear stage. The planet wheels 32 roll inside a ring gear 36. As a result, a first sun wheel 33 is rotated, which in turn, via a set of teeth 34, drives further planet wheels 35 of the second gear stage. The planet wheels 35 roll inside the ring gear 36 and drive a second sun wheel 37. The second sun wheel 37 is connected to the drive shaft 51 of the mechanical percussion mechanism 50 in a manner fixed against relative rotation.
To that end, in
The mechanical percussion mechanism 50 of
In nonpercussive driving, the percussion body 56 is prestressed in the direction of the driven shaft 59 via a compression spring 55. Then the drive cams 53 engage the driven cams 54 in such a way that the rotary motion of the percussion body 56 is transmitted to the driven shaft 59. The driven shaft 59 is likewise supported in a bearing 61. A shim 24 serves to receive and fix the compression spring 55 and also to protect the housing 20 against heating and wear from the friction of the compression spring 55. For receiving a tool insert (not shown), the driven shaft 59 is connected to a tool receptacle 62. The percussion mechanism 50 is received in a housing part 63, preferably of metal. A housing screen 64 of an elastic plastic covers at least some of the housing part 63.
The mode of operation of a V-groove rotary percussion mechanism will not be discussed in detail here, since it is familiar enough to one skilled in the art. As to the mode of operation, it will merely be indicated that by means of a screw (not shown) contacting a workpiece, the torque demand increases abruptly, and the rotary motion of the driven shaft 59 is blocked. The percussion body 56 driven by the drive shaft 51 continues to rotate and is pressed by the slaving elements 57 in the V-shaped grooves 58 in the direction of the drive end of the drive shaft 51, counter to the restoring force of the compression spring 55. In the process, the drive cams 53 of the percussion body 56 meet the driven cams 54 of the driven shaft 59, and the energy of the percussion body 56, stored as a result of the rotation, is therefore transmitted to the driven shaft 59. As a result of this longitudinal motion, the drive cams 53 slip farther on the driven cams 54 and slide past them.
For the sake of greater simplicity, the mechanical percussion mechanism 50 is shown in
Without an axial stop 70, the percussion body 56 could be moved still farther axially in the direction of the drive end of the drive shaft 51, so that the slaving elements 57 could be set free and fall out of the V-grooves 58.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above.
While the invention has been illustrated and described as embodied in a mechanical percussion mechanism, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.
Number | Date | Country | Kind |
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202006014850.7 | Sep 2006 | DE | national |