Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-12-14
2001-09-18
Ponomarenko, Nicholas (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S07500D, C310S098000, C310S096000
Reexamination Certificate
active
06291917
ABSTRACT:
PRIOR ART
The invention relates to an electric drive unit for windshield washers of a motor vehicle, including a drive motor having an armature accommodated in a substantially cup-shaped pole housing. A substantially cup-shaped gearbox is secured by its face end to the pole housing, for receiving at least one transmission gear wheel that meshes with a worm connected to an armature shaft of the armature. The armature shaft has a mushroom-shaped stop face on its face end, against which a spring for generating a defined initial stress comes to rest.
In such drive mechanisms, the armature shaft of the wiper motor must not have any axial play, because otherwise the entire drive mechanism is subject to considerable wear, and in particular irritating knocking noises occur.
One such drive unit is disclosed for instance in German Patent Application DE 195 08 306 A1.
In this drive unit, the axial play is eliminated by a prestressed leaf-springlike spring element, requires only a few steps in assembly in particular and to that extent can also be installed in an automated way and therefore especially inexpensively.
A problematic aspect of eliminating axial play by such a spring element is that the initial stress of the spring either cannot be varied, or can be varied only with a very great effort.
The initial stress is predetermined essentially by the shape of the leaf-spring like spring element and by its installed position.
It is therefore the object of the invention to refine an electric drive unit, especially for windshield washers of a motor vehicle, of the generic type in question in such a way that it is possible to set the initial stress of the spring element in a very simple way, and especially in conjunction with automated production.
Advantages of the Invention
In an electric drive unit of the typed described at the outset, this object is attained according to the invention in that the spring is a curved bending spring, which has a substantially V-shaped profile, with a tensioning plate secured in the gearbox and with a leg, yielding in the axial direction of the armature shaft, which in the installed state exerts a spring force, on the mushroom-shaped stop face of the armature shaft. The use of a curved bending spring, which has a substantially V-shaped profile, with a tensioning plate secured in the gearbox and with a leg, yielding in the axial direction of the armature shaft, which in the installed state rests, exerting a spring force, on the mushroom-shaped stop face of the armature shaft, has the particularly great advantage that precise setting of the initial stress is made possible along with a very simple assembly of the spring, which can also be done automatically,
Since it is known that the spring force is proportional to the spring deflection, the initial stress can be varied by the choice of the corresponding installed position.
The initial stress depends on how markedly the yielding leg is deflected out of its position of repose, in which the spring has a substantially V-shaped profile, toward the fastened tensioning plate.
In order to position and fasten the bending spring at a desired position in a simple way, and in particular also by automated production, it is preferably provided that the tensioning plate has lateral clamping elements, which in a recess provided for the purpose in the gearbox enable on the one hand an axial displacement of the tensioning plate toward the mushroom-shaped stop face and on the other a clamping fastening thereof in any desired position.
The spring constant of the bending spring, that is, its initial stress, is advantageously settable by means of the leg length, leg radius, leg width, leg thickness of the spring, and the axial positioning of the spring in the recess. This makes precise setting of the initial stress possible, along with a fast, unproblematic assembly.
The bending spring is preferably a stamped part and can therefore be made especially economically, including in great numbers.
REFERENCES:
patent: 4369387 (1983-01-01), Haar et al.
patent: 5386165 (1995-01-01), Bruhn
patent: 5945755 (1999-08-01), Ohmi et al.
patent: 6018223 (2000-01-01), Oruganty
Fischer Ernst
Hurst Richard
Greigg Edwin E.
Greigg Ronald E.
Lam Thanh
Ponomarenko Nicholas
Robert & Bosch GmbH
LandOfFree
Electrical drive unit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrical drive unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrical drive unit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2485026