Abrading – Frame or mount – Portable abrader
Reexamination Certificate
2000-12-11
2003-03-04
Eley, Timothy V. (Department: 3723)
Abrading
Frame or mount
Portable abrader
C451S259000, C451S358000, C451S359000, C451S451000, C030S500000
Reexamination Certificate
active
06527630
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electrical hand tool, in particular an angle sander, having a motor housing receiving an electrical drive mechanism, and with a housing element, which protrudes from the front face of the motor housing and is rotatably maintained on the motor housing.
BACKGROUND OF THE INVENTION
Electrical hand tools of the above mentioned type are known, for example, from DE German published application OS 40 22 668 A1. With these hand tools either the gear head or the handle are rotatably seated on the motor housing so that, depending on whether the user of the electrical hand tool is right- or left-handed, and depending on the position of use of the electrical hand tool, the handle can be rotated with respect to the housing, so that therefore ergonomically advantageous working is possible for all users and all positions of use.
It is disadvantageous in connection with the known electrical hand tools, that the structural length is too great because of the rotatable seating of the gear head or of the handle. Moreover, it is necessary to provide maintenance openings on the motor housing in order to be able to exchange parts subject to wear, such as carbon brushes, without having to disassemble the electrical drive mechanism. Trouble in regard to handling and a relatively complicated production of these electrical hand tools result from this.
OBJECT AND SUMMARY OF THE INVENTION
The object of the present invention is based on making available an electrical hand tool whose manipulation is improved and whose production and maintenance costs are reduced.
In accordance with the present invention, this object is attained by an electrical hand tool, in particular an angle sander, having a motor housing receiving an electrical drive mechanism, and with a housing element, which is rotatably maintained on the motor housing, wherein the housing element at least partially encloses the motor housing, and wherein the housing element has a maintenance opening in the area in which it encloses the motor housing.
Because the motor housing projects into the housing element, or is at least partially enclosed by it, the structural length is reduced and the manipulation of the electric hand tool in accordance with the present invention is improved by this. Moreover, it is possible to perform maintenance or simple repair work on the electrical drive mechanism simply and cost-effectively through the maintenance opening of the housing element. Because the housing element is rotatably maintained on the motor housing, one maintenance opening suffices for accessing the entire portion of the motor housing in the area enclosed by the housing element. In the end, the number of needed parts is reduced, and the mechanical load-bearing capacity of the hand tool is improved, since only one maintenance opening is required.
One embodiment of the. Present invention has an electrical drive mechanism with a commutator, wherein the housing element encloses the motor housing at least in the area of the commutator, so that the carbon brushes of the electrical drive mechanism, which as a rule are arranged offset by 180°, can be simply and cost-effectively replaced. In place of the two maintenance openings required in connection with known electric hand tools, only one maintenance opening is required with the electrical hand tool in accordance with the present invention.
A variation of the present invention provides that the maintenance opening can be closed off by means of a cover, so that dirt, dust and moisture cannot reach the area of the commutator.
Supplementing the present invention, it is provided that the maintenance opening is a recess, which is open toward the front face of the housing element facing the motor housing of the electrical drive mechanism, so that the manufacture of the housing element is simplified and therefore the production costs are further reduced.
In a further embodiment of the present invention it is provided that the housing element is made of two parts, and that the dividing plane divides the maintenance opening into two sections, so that the production of the two sections is simplified.
Variations of the present invention provide that the cover can be snapped into and/or screwed to one or both halves of the housing, as well as that the cover is pivotably seated on one of the two halves of the housing element. It is common to all of these embodiments that the fastening of the cover simultaneously fixes the two halves of the housing element to each other. Because of this, a fastening screw between the two halves of the housing element can be omitted, so that the number of parts is reduced and the production costs are further minimized. It can be particularly advantageous if for, example, the cover is snapped into one of the two halves and is screwed to the other half of the housing element, because a particularly simple and quick assembly and an assured fixation of the two housing halves, which can be stressed, is achieved by such a combination. If the cover is pivotably seated on both halves of the housing element, this prevents the loss of the cover when the maintenance opening must be opened for maintenance or repair purposes.
With another embodiment of the present invention, the housing element has means for sealing the interior of the housing element and the motor housing against dirt, dust and/or moisture in the area of the front facing the motor housing, so that the operational dependability and the service life of the electrical hand tool, in particular of the electrical drive mechanism, are increased.
In another form of the embodiment of the present invention, the housing element has at least one ventilation opening in the area of the commutator, so that cooling of the electrical drive mechanism is improved. With electrical hand tools of the prior art it is necessary to provide the maintenance openings closed with a cover in place of ventilation openings.
In a further embodiment of the present invention, the maintenance opening is arranged on the top or underside of the housing element, when the electrical hand tool is in a horizontal position of use, so that dust raised from the workpiece, or dust falling from above on the electrical hand tool, or the like, cannot enter the interior of the housing element, because as a rule the maintenance opening is closed off by a cover during operation.
In connection with a variation of the present it is provided that the ventilation opening or ventilation openings are arranged on one or both sides of the housing element, when the electrical hand tool is in a horizontal position of use, so that the grinding dust lying on the workpiece or the like is not raised, and furthermore the air flow passing through the ventilation openings is not blown directly on the user.
A form of embodiment of the present invention provides that the housing element is a gear head with a tool receiver, so that no electrical connections or electrical lines must follow the rotary movement of the housing element in relation to the electrical drive mechanism, and therefore a high functional dependability is achieved.
In another embodiment of the present invention the housing element is a handle, in particular with a switch panel for switching the electrical drive mechanism on, so that the connection between the gear head and the electrical drive mechanism can be designed to be especially rigid.
A further embodiment of thee present invention provides that the housing element has at least one radially projecting collar, which engages at least one circumferential groove in the motor housing, so that large forces, or moments, can be transmitted between the motor housing and the housing element.
Further advantages and advantageous embodiments of the present invention can be taken from the following description, the drawings and the claims. An exemplary embodiment of the subject of the present invention is represented in the drawings and explained in greater detail in what follows.
REFERENCES:
patent: 5347765 (1994-09-01), Mixon, Jr
Mannsperger Reiner
Tiefenbach Thomas
Eley Timothy V.
Jones Tullar & Cooper P.C.
McDonald Shantese
Metabowerke GmbH & Co.
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