The invention relates to a drive device for a wiper arm of a windscreen wiper unit according to the preamble of claim 1.
Drive devices for windscreen wiper assemblies or units are known, in which a linkage system is provided in the drive train between a windscreen wiper motor and a wiper arm or a vehicle-mounted wiper shaft, via which linkage system the movement of a drive train of the windscreen wiper assembly, driven at one end by a crank, is translated into a backwards and forwards rotary motion, i.e. into a reversing motion, of the wiper shaft. This linkage system hereby comprises two pivot arms, each of which is coupled at one end with a rocker and at the other end with the drive train moved by the crank. Permanently connected to the rocker is the wiper shaft, so that the latter and, along with it, the wiper arm, are pivoted about the axis of the wiper shaft.
One of the disadvantages of the known drive devices is the fact that the wiper arm executes a purely pivoting movement about the vehicle-side axis of the wiper shaft, which leads in many cases to an unsatisfactory wiping field being swept by the wiper arm or by a wiper blade present there. One of the reasons in particular why this applies is that, for design reasons, vehicle windows, especially including rear vehicle windows, are nowadays frequently configured with a small height dimension and a relatively great width, or, conversely, with a relatively great height in relation to the window width, so a pivoting motion of the wiper arm about the central axis of the wiper shaft purely in the shape of the arc of a circle leads to this unsatisfactory wiping field, in which a not inconsiderable proportion of the vehicle screen is not swept at all by the wiper arm or wiper blade.
It is the object of the invention to indicate a drive device with which, along with the opportunity of low-cost production and a robust, operationally-reliable design, an enlargement and adaptation or optimisation of the shape of the wiping field covered by the moved wiper arm or the wiper blade present there is achieved. A drive device according to claim 1 is developed to achieve this object.
Owing to the design according to the invention, the wiper arm is pivoted, during operation of the windscreen wiper assembly, about the central axis of its fastening to the rocker constituting part of the linkage system, and simultaneously the central axis of the fastening of the wiper arm is moved along a path. The shape of the path on which the central axis of the wiper-arm fastening is moved can be influenced, in particular, by the geometry and/or the orientation or arrangement of the linkage system, in such a way that an optimum wiping field is achieved for the particular application, in other words a wiping field enlarged in width in the case of especially wide vehicle screens, for example.
The drive device according to the invention is especially suitable for rear windows of vehicles, but may also be used in other screen wiper assemblies. Developments of the invention are the subject-matter of the dependent claims.
The invention is explained in greater detail below with reference to example embodiments in the Figures. They show:
In the Figures, 1 is a linkage system, which essentially consists of a mounting plate or bearing element 2, which is oblong-shaped in the embodiment shown, of two pivot arms 3 and 4, and of a rocker 5, to which the wiper arm 6 is fastened with rotational resistance with its end 6.1.
In the embodiment shown in
In detail, the linkage system 1 is designed in such a manner that the pivot arm 3 is connected at one of its ends to the shaft 9 of a reversing electromotive drive or windscreen wiper motor, which is otherwise not further shown. The other end of the pivot arm 3 is connected via an articulation 10 to one end of the rocker 5. The pivot arm 4 is coupled at one end with the bearing element 2 via an articulation 11 and connected at its other end to the other end of the rocker 5 via an articulation 12. Provided between the two articulations 10 and 12 is a fastening or retaining element 13, which in the embodiment shown takes the form of a peg anchored with rotational resistance to the rocker 5, to which the wiper arm 6 is then fastened with rotational resistance at its end 6.1, e.g. in the same manner as occurs in the case of conventional fastening to a wiper shaft.
The axes of the articulations 10-12 and the axis of the shaft 9 as well as the axis of the retaining element 13 are parallel with one another and, in the installed state, are orientated normal to or roughly normal to the plane of the vehicle screen 8. The configuration is further arranged in such a manner that, in the central position of the wiper arm 6 and the linkage system 1 as shown in
Furthermore, the axes of the shaft 9 and of the articulation 10 are arranged in a common plane E2 running normal to the plane of projection of
Articulations 10 and 12 as well as the fastening element 13 are, in the central position, located on a common side of plane E1, wherein articulations 10 and 12 exhibit the same, smaller distance, and the fastening element 13 a somewhat greater distance from plane E1. Furthermore, in the central position relative to the arrangement of the articulation and pivoting axes, the linkage system 1 is in mirror symmetry to a central plane M, which is arranged parallel with these axes and encloses the longitudinal dimension of the wiper arm 6.
In the embodiment shown, the linkage system 1 is defined geometrically by the following dimensions:
wherein a unit is, for example, 1 mm.
To generate the laterally enlarged wiping field extending between the lines 7.1 (
With the electromotive drive switched on, the pivot arm 3 is reversibly pivoted about the axis of the shaft 9, as a result of which, as shown in
The situation of the wiper arm 6 and the positions of the articulations 10 and 12 for the pivoting of the linkage system 1 out of the central position in one direction are also indicated in
The invention has been described above with reference to example embodiments. Numerous modifications and alterations are of course possible without the inventive concept on which the invention is based being abandoned.
For example, it is possible for the bearing element 2 to be of a design other than oblong-shaped. It is furthermore possible for the bearing element 2 to be provided directly on the electromotive drive and/or for the articulation 11 to be arranged on a housing of this drive. The shaft 9 is, for example, the output shaft of a reversing windscreen-wiper motor or geared motor, but may also be a shaft mounted on the vehicle, which is reversibly driven by, for example, a crank drive.
Number | Date | Country | Kind |
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10 2004 026 552.6 | May 2004 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP05/05557 | 5/23/2005 | WO | 00 | 1/30/2008 |