Abrading – Frame or mount – Portable abrader
Reexamination Certificate
1999-12-15
2001-09-25
Hail, III, Joseph J. (Department: 3723)
Abrading
Frame or mount
Portable abrader
C451S358000, C451S359000, C451S360000
Reexamination Certificate
active
06293859
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a power tool, in particular a right-angle grinder, having an elongated motor housing in which an electric motor is received, having a gear drive housing at a first end of the motor housing to receive a gear drive for driving a working spindle, and having a handle element which is fastened rotatably at a second end of the motor housing and in which a grip switch is arranged.
A power tool of this kind is known from DE 195 46 328 A1.
The known power tool is configured as a right-angle grinder, and has a yoke-shaped handle element, having a grip switch, that is fastened rotatably at the end of a motor housing and is rotatable with respect to the motor housing into a total of three angular positions, each offset 90° from one another. This makes it possible for both right-handers and left-handers to hold the right-angle grinder in a particularly ergonomic fashion, if it is considered that in the front region of the motor housing, a second handle of rod-shaped configuration can additionally be threaded onto the housing, selectably on the right or left. A rotation capability of this kind further makes it possible to alternate the right-angle grinder between cutoff grinding and rough grinding; in the case of cutoff grinding, it is possible to work selectably either with a grinding spindle projecting to the right out of the gear drive head, or with a grinding spindle projecting to the left out of the gear drive head.
For immobilization in the various angular positions, recesses into which a locking element, preloaded in the axial direction, engages are provided at the end of the motor housing facing toward the handle element. When the handle element is to be rotated out of one angular position into another angular position, a handle must first be actuated in order to release the locking element in the axial direction, against the spring tension, out of the relevant recess, so that the handle element can be rotated until the locking element snaps back into a projection in the next predefined angular position.
In a further power tool that is known from DE 40 21 277 A1 and can be used as a cutoff grinder, hedge clipper, brush cutter, or motor-driven chain saw, a yoke-shaped handle at the end of a motor housing is also adjustable into three different angular positions offset 90° from one another, into which it can snap. Provided for snap-locking is a catch pawl, mounted on the handle, that engages with a projection into a corresponding depression of the motor housing and is loaded by a spring in the direction of an immobilization position.
SUMMARY OF THE INVENTION
It is the object of the invention to create an improved power tool such that the disadvantages of the existing art are avoided and ergonomic operation, with the widest possible working range, is made possible.
In a power tool of the kind defined initially, this object is achieved according to the present invention in that the handle element is rotatable with respect to the motor housing into at least four predefined angular positions and can be snap-locked in them.
The object of the invention is completely achieved in this fashion. The present invention overcomes the prejudice, existing in the related art, that it is sufficient for all applications to rotate a rotatable handle element with respect to the motor housing from a center position into one further working position to the left or into one other working position to the right. The present invention, specifically, now makes possible a further working position in which the handle element can be rotated, for example, 180° with respect to its normal position, while two further working positions are possible in which a rotation out of the normal position takes place only 90° clockwise or counterclockwise, respectively.
These additional angular positions facilitate work, in particular, on ceiling areas. Roughing work on ceiling areas occurs, for example, in rail car construction. In this, the right-angle grinder must be held above the head so that parts can be deburred or the like. The present invention greatly facilitates such work, since the handle element can be rotated 180° with respect to its normal position. Further advantages are offered when the right-angle grinder is used in stationary fashion.
In an additional development of the invention, a rotation angle limiter is provided between the motor housing and handle element to limit the maximum rotation angle between the motor housing and the handle element.
This feature prevents the handle element from being rotated several times with respect to the motor housing, which might result in damage to the electrical connecting lines between the handle element and motor housing.
In an advantageous development of the invention, the grip switch has a grip button that is locked to prevent actuation if the handle element is not in one of the predefined angular positions and snap-locked to the motor housing.
This prevents the power tool from being switched on if the handle element is not in a stable position with reference to the motor housing, thus preventing inadvertent rotation of the handle element with respect to the motor housing while working, with the associated risk of accident.
According to a further embodiment of the invention, there is provided on the motor housing a central annular flange in which radial recesses are provided into which a projection of a locking lever, mounted pivotably and preloaded into an immobilization position, can snap-lock in each of the respective predefined angular positions.
This results in a particularly simple immobilization capability for the handle element in the predefined angular positions on the motor housing, and moreover yields a particularly space-saving construction. The result is to prevent the handle element from rotating unintentionally. If a rotation of the handle element into a different angular position with respect to the motor housing is desired, it is instead necessary first to press down the locking button, whereupon the handle element can then be rotated with respect to the motor housing until the locking button once again engages, in one of the predefined angular positions, into one of the radial recesses on the motor housing and locks the handle element to prevent further rotation with respect to the motor housing.
In an additional development of the invention, there is additionally fastened on the handle element, pivotably on a pivot shaft, an immobilization lever that has a first part, protruding from the pivot shaft toward the motor housing and configured as a pushbutton, at whose outer end is configured a projection that can be introduced into one of the recesses of the flange; and that has a second part, protruding from the pivot shaft approximately at right angles to the first part, that coacts with the grip button of the grip switch in such a way that the grip button can be pushed in to switch on the motor only if the pushbutton has previously been transferred into an activation position by being pressed in, so that the projection of the immobilization lever engages into one of the radial recesses on the annular flange of the motor housing.
In this fashion, unintentional activation of the right-angle grinder when the grip switch is grasped is avoided with simple means. A user must first push down the pushbutton before he or she can actuate the grip button of the grip switch.
In an additional development of this embodiment, the grip button is fastened pivotably at the end of the handle element facing away from the motor housing and preloaded against a movement into an activation position to switch on the motor, and has at its free end a web that, in a catch position when the pushbutton is not pushed in, stops against a projection on the second part of the immobilization lever so as to prevent actuation of the grip button to switch on the motor.
In an additional development of this embodiment, when the pushbutton is pushed in, the grip button is movable against a spring force past the projection into the a
Fink Manfred
Rudolf Boris
C. & E. Fein GmbH & Co.
Cummings & Lockwood
Hail III Joseph J.
Nguyen George
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