Electrical hand tool machine with vibration damped striking mechanism

A partially percussive electrical hand tool machine (1) having a portable housing (3), a striking mechanism module (4) connected, in a vibration-damped manner, to the housing (3) and having electrical lines (5) for electrical connection of the relatively moveable striking mechanism module (4) to the housing (3). The electrical lines (5) are non-vibrationally attached in a bending flexible wiring bridge (7) arranged transverse to the striking axis (A).

BACKGROUND OF THE INVENTION

The invention relates to an at least partially percussive electrical hand tool machine having a portable housing and a striking mechanism module vibrationally-damped thereto, in particular a chisel hammer.

The pneumatic striking mechanism, in percussive electrical hand tool machines, usually driven by an electric motor and the interaction of the work piece with the percussive tool cause inertia-related vibrations that are transmitted through the housing to the operator, in the frequency range of 1 Hz to 100 Hz, which should be suppressed as much as possible. These type of striking mechanism modules that are vibration-damped using a spring to the housing are limited displaceable, approximately 10 mm, for producing a different pre-stressing along the striking axis and vibrate about this central position with an amplitude of a few millimeters.

According to GB 215 4 497, an electrical hand tool machine has a striking mechanism module that is vibration damped by the housing, wherein the electrical motor that is solidly connected to the housing has a limited moveable engagement along the striking axis in the striking mechanism module.

According to DE 100 0 8671, the electrical motor, in an electrical hand tool machine, is connected to the housing via long, freely suspended lines. Such long, freely suspended lines have a very low resistance to bending because of their punctiform cross section and have a low intrinsic resonance relative to bending vibration modi, which can undergo a resonant excitation in the event of vibrations and which can result in failure due to material fatigue.

In addition, according to EP 0 276 313, a flat ribbon like cable harness between parts of a robot limited moveable relative to each other has a moveable flat rigid supporting structure, to which the cables are fastened. According to U.S. Pat. No. 5,054,944, a moveable printing head has a flat ribbon like cable harness that is flexible in one dimension and is a flexible circuit board made of plastic, which extends along the movement.

SUMMARY OF THE INVENTION

The object of the invention is to provide a vibration-damped striking mechanism module with a low-fatigue current supply.

This object is achieved, in accordance with the invention, by an at least partially percussive electrical hand tool machine having a portable housing and a striking mechanism module that is vibration damped relative to the housing has a plurality of electrical lines for electrical connection to the striking mechanism module that is limited displaceable relative to the housing, wherein the lines are non-vibrationally fastened in a flexible wiring bridge arranged transverse to the striking axis.

The individual lines fixed in the non-oscillating flexible wiring bridge arranged transverse to the striking axis form with the wiring bridge a virtually vibration-free module, which is more rigid than a single line and has essentially higher bending intrinsic vibration modi that are separated from the excitation spectrum in the frequency range to prevent resonant excitations.

Advantageously, the wiring bridge has a plurality of longitudinally separated guide means for individual locking guidance of the line and fastening means that can be attached, preferably clipped on, such that the lines can be fastened to discrete sites.

Advantageously, the wiring bridge is flexibly bent relative to one bending axis oriented transverse to the striking axis and in another rigidly configured, as a ribbon, whereby transverse vibrations are suppressed.

Advantageously, the wiring bridge is made of plastic, preferably unreinforced polyamide, whereby a high and low-fatigue vibration damping results via the viscoelastic behavior.

A plug connector that can be displaced along the wiring bridge is arranged at the terminus of the wiring bridge, whereby with the non-vibrational assembly, a latent stress-free fastening relative to the wiring bridge can be made.

Advantageously, a friction-locking fastening of the plug connector to the wiring bridge is practiced using an intervening rib, whereby the plug connector can be fixed and displaceable using an assembly screw.

Advantageously, the wiring bridge projecting at one side is secure with the electronics module, preferably bonded to the electronics module via a casting mass, whereby the wiring bridge is a pre-installable part of the electronics module.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a rotary and percussive electrical hand tool machine1having a housing3portable using a handle2and a striking mechanism module4relatively limited moveable along the striking axis A and connected vibration-damped thereto has a plurality of flexible, electrical lines5, which connects the housing3and the striking mechanism module4, which contain an electrical motor. The lines5are non-vibrationally attached to a wiring bridge7arranged transverse to the striking axis A, which is connected projecting and secure with an electronics module12, in that is bonded to said latter via a casing mass13. A plug connector10non-vibrationally mounted at the terminus of the wiring bridge7connected the electronics module12electrically with the electrical motor6.

According toFIG. 2, the lines5are fastened non-vibrationally, in a defined bending flexible wiring bridge7, arranged transverse to the striking axis A, relative to precisely one bending axis B oriented transverse to the striking axis A. When this is done, the bending flexibility by virtue of a suitable thickness of the wiring bridge7is chosen such that the first bend intrinsic vibration of the wiring bridge7configured as a ribbon made of polyamide, is greater than 200 Hz relative to the bend axis B. The wiring bridge7has a plurality of longitudinally spaced guide means8for individual locking guidance of the lines5and clip fastening means9for fastening. The plug connector10, which is displaceable along the bridge, in the zone X, is arranged at the terminus of the wiring bridge7, which is fixed using two intervening ribs11locked, in a friction manner, to the wiring bridge, such that the plug connector10, which is mounted, in a non-vibrating manner, on the electrical motor6using screws14, creates a pressure bias via the ribs11.