Tool driving or impacting – Means to drive tool about an axis – Electric motor
Patent
1999-01-25
2000-09-26
Vo, Peter
Tool driving or impacting
Means to drive tool about an axis
Electric motor
173117, 173170, B25D 1300
Patent
active
061231584
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an electric tool which is driven by an electric motor 1.
Electric tools of this type are known.
In the known electric tools of the generic type, the variable-speed drive is realised as a rule by via a collector motor whose drive voltage is set in a fashion guided either by speed or by value prescription, and is thus adjusted to a desired speed.
The current is fed to the collector of the collector motor via carbon brushes, with the result that both the collector and the carbon brushes are subjected in practice to substantial wear and, because of the unavoidable considerable heating of the collector under the flow of current between the brushes and the collector, the rotor winding is at risk of failure through overheating and vibrational damage, and constitutes the thermally most critical component in the known electric tools.
It is known that, by contrast with collector motors, three-phase ac motors (asynchronous or synchronous motors), magnetic motors and reluctance motors are considerably lower in wear, and that their thermal loading is substantially easier to manage in operation than that of collector motors. Hitherto, the use of three-phase ac motors in electric tools of the aforementioned type has so far been out of the question, because three-phase current is frequently not present at the place of use, or at least is not available at the required voltage and/or frequency (for example 250 V/200 Hz; 42 V/200 Hz).
OBJECT AND SUMMARY OF THE INVENTION
It is the object of the invention to create an electric tool of the generic type described above which is distinguished by a susceptibility to wear and thermal loading of its electric motor which is lower by contrast with the known tools of the generic type, as well as by a robust and maintenance-free design and, in addition, is configured such that there is no risk of any sort of overheating even for the components provided for supplying the drive energy for the electric motor in the tool housing.
The above object is achieved by mounting the frequency converter in a handle part of the motor housing in a location in which a cooling surface of the frequency converter is located in a cooling air path that extends through the handle part, over the cooling surface of the frequency converter, and into the motor compartment.
In the case of the electric tool in accordance with the invention, because of the inventive installation in the housing of the tool of an electronic control system which is fed on the input side with the single-phase alternating current and supplies the type of current required by the motor on the output side, virtually any brushless and slipring-less and thus wear-resistant and heat-resistant electric motor can be used as a drive motor, and the electronic control system is moreover, according to the invention, installed in the tool housing in such a way that for it, as well, the risk of overheating is reliably excluded.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in more detail below with the aid of the drawing and with reference to an exemplary embodiment. The sole FIGURE of the drawing shows the tool in a diagrammatic representation in longitudinal section.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The tool represented in the drawing is a percussion hammer/hammer drill which has a housing 1 in which there is installed an electric motor 2 which drives the percussion mechanism 3a, which is provided with a crank mechanism 3, is not shown in more detail, and can be of known design.
The electric motor 2 is a brushless and slipring-less motor which obtains its drive energy from an electronic control system 5 which on the input side is fed with the single-phase alternating current 4a, and on the output side supplies the type of current 4b required by the motor, a hand-operated switch 6 being connected upstream of the electronic control system 5 for the purpose of switching the motor 2 on and off.
The electric motor 2 can be of any known design of speed-controlle
REFERENCES:
patent: 3430709 (1969-03-01), Miller
patent: 3718193 (1973-02-01), Wanner
patent: 3824417 (1974-07-01), Moores, Jr.
patent: 4094365 (1978-06-01), Wanner
patent: 4156468 (1979-05-01), Stiltz et al.
patent: 4489261 (1984-12-01), Hartwig et al.
patent: 4601351 (1986-07-01), Hartwig et al.
patent: 4711308 (1987-12-01), Blaas et al.
patent: 4766963 (1988-08-01), Hartwig et al.
patent: 5014794 (1991-05-01), Hansson et al.
patent: 5165488 (1992-11-01), Liu
Calve Jim
Vo Peter
Wacker-Werke GmbH & Co. KG
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