Working tool which can be guided in a grab handle

Details Working tool which can be guided in a grab handle Working tool which can be guided in a grab handle

1998-10-08

2000-06-20

Vo, Peter

Tool driving or impacting

Including means to vibrationally isolate a drive means from...

Handle type holder

173211, E21B 300

Patent

active

060766166

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a tool which can be guided using a handle, having an operating element that is driven by an integrated power drive for the percussive, pounding or vibratory loading of a material to be worked, in particular a tamper, vibration plate or vibration roll for ground compaction or a hammer for breaking and/or drilling operations.
2. Discussion of the Related Art
In the case of devices of this type, the transmission of the shocks or vibrations to the handle is not only unpleasant but also damaging to health, for which reason the operating time is limited in accordance with the intensity of this action. Trouble is therefore taken to keep the oscillations of the handle as small as possible.
For this purpose, at present only a passive reduction in oscillations by spring-damper elements and inertial masses is known, which is accompanied by the disadvantage that a large reduction in oscillations is possible only via large spring travels, which, for its part, in turn impairs the ability of the tool to be guided, and that a high efficiency of the reduction in oscillations is achieved only at high frequency ratios .omega..sub.exciting /.omega..sub.inherent.
EP-A-206 981 discloses a hand-held tool having an oscillation generator to which there is fastened a handle that can be displaced to a limited extent between two stops, parallel to the main oscillation axis. The stop for the handle which is arranged in the advance direction of the hand-held tool is designed as an electromagnet, the electromagnet being operated with an essentially constant direct current and producing a force which counteracts the contact pressure applied by the operator. The force of the electromagnet is controllable, in order to enable adaptation to the conditions which depend on the orientation of the hand-held tool.


OBJECTS AND SUMMARY OF THE INVENTION

The invention is based on the object of overcoming these disadvantages of the previously common reduction in oscillations at the handle that is to say to achieve a reduction in oscillations without large spring travels and with a high efficiency, even at low frequency ratios.
In the case of a tool of the type cited at the beginning, this object is achieved in that the handle is actively vibration-damped by at least one actively controlled or regulated compensation element, which counteracts the transmission of a vibration to the handle and which, depending on the vibration that can be transmitted to it and is produced in and/or on the tool, produces a compensating force and/or movement in the potential vibration transmission path from the location of production of the vibration to the handle.
As a result, over the entire frequency band, a high efficiency of the reduction in oscillations is achieved, irrespective of the contact pressure. The ability of the tool to be guided is not impaired by soft spring/damper elements. No large inertial masses are necessary, which would otherwise have an effect on the total weight of the device and in addition and possibly exhibit undesirable resonance phenomena.


BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail below using exemplary embodiments illustrated in the drawings, in which:
FIG. 1 shows a section through a breaker or hammer drill designed in accordance with the invention,
FIG. 2 shows a detail section through the end of the tool having the handle, on an enlarged scale, and
FIGS. 3A-3H show a schematic view of different embodiments of a device according to the invention.


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrated in FIGS. 1 and 2 is a breaker and/or hammer drill H which is configured in accordance with the invention and has a handle GR with a power feed S and an on/off switch EA that is actuated by means of a push button TA. Accommodated in the handle GR is a regulating and control unit RSE, whose function will be explained further below. Via a first joint G1 having a first spring/damper element FD1, and a second joint G2

REFERENCES:
patent: 2425245 (1947-08-01), Johnson
patent: 4237987 (1980-12-01), Sherman
patent: 4282938 (1981-08-01), Minamidate
patent: 4421181 (1983-12-01), Andersson et al.
patent: 4478293 (1984-10-01), Weilenmann et al.
patent: 4711308 (1987-12-01), Blaas et al.
patent: 4749049 (1988-06-01), Greppmair
patent: 4800965 (1989-01-01), Keller
patent: 5025870 (1991-06-01), Gantner
patent: 5052499 (1991-10-01), Dobry et al.

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